Ok so The Survivors Titans scale to 1.255 Kilotons, and Steve scales to just over 3, giving Steve an AP advantage, but not a huge one.
Steve does have a pretty huge Hax advantage, but if the Survivor has all 3 titans and his Mek, there's a good chance that Steve is gonna get swarmed pretty quickly considering how the Survivor sends his creatures in.
The Ice Titan could be a problem, Steve doesn't resist Ice Manipulation, so there's a good chance he gets frozen at the start, granted he'll have the Elytra, so it could be difficult.
The Desert Titan is gonna swarm him with weaker flocks and strike lightning which could hurt Steve with a good shot.
The Forest Titan likely isn't gonna help hugely, but it could restrain Steve with its vines if it can catch him, Forest Wyverns will be a decent distraction too, but that's about it.
The Survivor will be in their Mek, which isn't gonna do much tbh except buy the Survivor some time. Steve has the AP and Hax to deal with it pretty quickly.
Steve does have a pretty big hax advantage, but in this case, I don't see him taking on 3 Titans and a Mek at once. Even with his endgame gear. He's gonna get pummeled at the start pretty quickly and either frozen, incapped, or simply bombarded completely.