I think that when Yuta says "He is stronger than me when on a roll" he means Hakari's scoring multiple Jacklots in a row.
Both Yuta and Hakari have an "Hella CE" mode.
Yuta's lasts a bit longer than Hakari's, but Hakari can potentially reactivate over and over.
My guess is that as long as Hakari gets enough Jackpots to outlast him he'll win.
This is gonna be a somewhat long post since I'm dropping alot of what i've observed in one go rather than across multiple posts.
As far as we know, Hakari doesn't get buffed from having multiple Jackpots in a row. The 3 Jackpots we've seen him hit all have the same effect so far (unfortunately, I wish he had more abilities. Then again we haven't seen his CT and he's not trying to kill Kashimo). So basically, as far as we know as of 189, it's Jackpot Hakari in general who's stronger than Yuta.
But I think Hakari is strong enough to just blatantly stat bully Yuta. Jackpot Hakari is physically superior to Kashimo by a large margin. Speedblitz levels of speed even (as shown at the end of 188 before he got hit with kashimo's return stroke). Kashimo should be relative to or above Ishigori and Uro. Uro was able to tank a barrage from 5 Minute Mode Yuta using a CT Gauntlet which more than likely increased his striking strength, and Rika who's physically stronger than Yuta at the same time, and she was in perfect fighting shape still. I think she hit Yuta maybe 4 or 5 times during the fight, and Ishigori noted that Yuta had to use Reverse Cursed Tech to heal from all their big moves. She also slightly outsped Yuta in their CQC exchange since she was able to make the hand motions for her CT and then strike Yuta with her hands before Yuta was able to properly land a blow on her. That and she was defeated by all 3 of them combo attacking her.
As for Ishigori, he was pretty much holding back and still overpowering Yuta in CQC even though Yuta was the one to bring the fight to him. And even then, Yuta needed to use RCT after all their big attacks. (It wasn't always shown but Ishigori noted that he did.) We know he wasn't going all out because when Rika first appeared, he shot a Granite Blast at her, and she caught in her hand which caused him to think she's more durable than Yuta is. Then, in chapter 180, he hits Rika with a full power punch (after he told Yuta he was gonna finish the fight now), and in the official translation, the narrator literally said that even if Rika was fully manifested, that punch would've one shotted her. And Yuta doesn't technically 'scale' to Ishigori either. He hit him with Uro's Thin Ice Missile while he wasn't exactly prepared to defend it, and then let Ishigori hit himself with Granite Blast. Rika hurt him to some degree, but he literally one shot her right after, so idk if it's right to say she scales if the Narration went out of it s way to say he would've one shotted her regardless of if she was on the verge of disappearing or not.
As for how this relates to Hakari, Kashimo is basically implied to be the strongest opponent so far which is consistent with Gege outside of the story and Yuta inside the story saying Hakari is stronger than Yuta. But without using that statement for circular scaling, Kashimo should scale to or above the person that one shot Rika. Kenjaku even implied some relativity to an old and dying Kashimo and a potentially prime Ishigori.
As for speed, idk if anyone calced it, but in 186, Hakari reacted to and slightly avoided Kashimo's lightning bolt while he was off guard and after it was inches away from his head. He moved in time for it to hit his arm instead. Kashimo in 186 scales to this casual Jackpot Hakari in terms of speed. Then, Kashimo turns up and amps his stats in 187. In 188, casual Jackpot Hakari is still relative to this turnt up Kashimo that's faster than he was in 186 when he kept up with an even more casual Hakari. He was even able to react to getting hit in the brain with lightning and countering it via expelling it from his nose before his brain got destroyed. (more so a reaction feat than combat speed in this scenario). Then, near the end of 188, Hakari moves so fast that Kashimo is not moving from his perspective while he's throwing barrages, and then when Kashimo tries to retaliate, Hakari literally disappears from his perceptions like a Bleach Flash Step, then appears back in place and continues attacking.
So Jackpot Hakari Actually Trying > 'Turnt Up' Chapter 187188 Kashimo ~ Casual Chapter 188 Hakari > Casual Chapter 186 Hakari ~ 'Base' Chapter 186 Kashimo ~ lightning timing from a very disadvantageous position while off guard
I don't know if there's a calc for that, but feat wise that's clearly above the speed of anyone else in the series as far as I know, and I don't think it scales to anyone.
So AP Wise, Hakari can damage and draw blood from both casual and turnt up Kashimo and overpowered him when actually trying. Similar or greater damage than Yuta with a CT and Rika did to Uro who should be weaker than Kashimo while she was affected by Cursed Speech and couldn't defend
Durability Wise, Hakari actually trying never got hit by Kashimo, but other than his CT and the face scrape, Hakari never needed to use RCT against his attacks. Even base Hakari was able to survive 187 Kashimo trying to kill him with physical strikes while Hakari himself was being nerfed by the electric CE and was still just barely able to fight back. Compared to Yuta that needed to use RCT for Kurorushi, Uro and Ishigori. Granted, Kurorushi has dura neg, but Uro and Ishigori seemed to be raw ap. Not sure about thin ice missile tbh but she hurt Yuta with a physical strike and was relatively fine after his and Rika's barrage, and purely physical augmentation should scale to striking strength style ap and dura
Speed wise, Hakari when actually trying completely blitzed kashimo and scales a few internal scaling chain layers above whatever that lightning timing feat would be. Base Hakari was able to move somewhat relative to but slower than a non turnt up Kashimo while being nerfed (shock/paralysis etc) by simply touching Kashimo while his electric CE was flowing. Yuta doesn't have any feats scaling to this level of speed and can't exactly scale since he said and Gege implied Hakari is above him.
And finally, if we're gonna talk about the narrator saying that Yuta is 2nd to Gojo or Naobito being the fastest etc. The narrator actually said Yuta is second to Gojo in terms of 'unusual abilities', not just in general. As for Naobito, it was said that he was known as the fastest sorcerer, but it's debatable how much is known about Hakari's Domain and exactly how much it buffs his stats etc. Naobito was said to be the fastest due to hus CT and his exceptional timing. Naoya has the same CT, which in verse scaling wise, not VS battle wiki wise is in the Speed of Sound range, give or take. He just doesn't have the same timing as his father. So they should be relative CT wise, and the CT can still be threatened by things like Piercing Blood etc. As for Kashimo, it's been pretty hammered in how saying his CE is like electricity isn't just a comparison, but has the actual properties of electricity as much as fiction would allow at least. And his CT has been blatantly called a lightning bolt
Between statements, scaling, and feats, Hakari really does have alot going over Yuta