ok so stats wise, yixuan has the general advantage here, 448 tons vs. 123 tons and 1,313 tons vs. 424 tons. pathfinder can amp themselves, but yixuan can also, so i'd say that likely evens out.
pathfinder has an absurd amount of versatility with every single attunement. i don't think stuff like flamecharm, frostdraw or thundercall are things that would catch her off guard too much given fire, electricity and ice are already pre-existing elements in ZZZ, but stuff like galebreathe, shadowcast, ironsing and bloodrend might trip her up a bit. going through the notable abilities on their profile i think might give yixuan trouble
paralysis inducement - yixuan can't really resist this, a second stun gives the pathfinder a good opportunity to set up attacks or stop her from attacking them
teleportation - spark swap could definitely trip yixuan up and could net an easy ringout if executed properly. dustlunge and air counter are also great ways to instantly teleport to yixuan as a way to counter her mobility
regen - potions could help keep the pathfinder in the fight, and i'd say they're generally more reliable than yixuan's own healing
energy absorption - might be helpful in dealing with yixuan's energy-based attacks
intangibility/invulnerability - two seconds of invulnerability can be pretty helpful for getting out of dangerous situations
gravity manipulation - can definitely help against yixuan's mobility, but i'm not sure how well it'd work thanks to yixuan's superior LS
healing/regen negation - definitely a very useful tool to stop yixuan from healing herself
supernatural willpower - useful in that it'll just help the pathfinder keep fighting
magic negation - if you equate ether-based attacks to magic, this seems like it will be very useful. not sure how long the negation lasts though, but it'll definitely limit a majority of yixuan's options
damage transferal - will be very useful in throwing back damage at yixuan
madness/fear manip - this seems like a big one, as yixuan doesn't resist this, but i'd need to know how fast it takes to set in. if the insanity isn't instantaneous (which iirc i don't think it is), it's possible yixuan could beat the pathfinder before she goes insane.
soul manipulation - yixuan doesn't really resist soul attacks so yeah, getting hit by the witherblade or soulthorn would probably be pretty bad
attack reflection - very strong, it's gonna mean yixuan is going to take a lot of the damage she's dishing out back at her
pathfinder has a loooot of options that are going to be very useful here, but i don't think yixuan is completely outclassed. outside of generally having the edge stats wise, her insane mobility is also going to be very useful here considering the fact that she can both fly and teleport. obviously, pathfinder can also teleport, and can also teleport straight on top of her via things like air counter and dustlunge, but i'm not sure if those are spammable, which means that generally, yixuan should still be able to keep her distance and play keep away if necessary, coupled with her various ranged attack options.
yixuan should be able to at the very least match a lot of the pathfinder's abilities with her own (martial arts, acrobatics, social influencing, enhanced senses, danmaku, forcefield creation, stat boosting/reducing, dura/resistance neg), but while pathfinder does actually resist a lot of the effects of ether corruption, i don't think they'd be able to resist the eventual transformation into an ethereal, which yixuan could induce with enough accumulation of her ether attacks. perception manip is also something i don't think pathfinder resists which also seems like it'll probably be useful in messing with their senses. power null would probably be useful to shut down some of the pathfinder's options, you could maybe argue stuff like sealing and matter manipulation would be able to just straight up oneshot but these haven't really been used in combat scenarios so i probably wouldn't hold them as super strong wincons.
i think yixuan's biggest asset though is vital view. it just means yixuan can react to and dodge any of the pathfinder's attacks, and in that time she can either position herself or counterattack as needed. considering how massive of a speed/perception amp it gives her, i'm not really sure if the pathfinder really has any way around it. i think considering yixuan's own intelligence as well, as the fight progresses she'd likely be able to intuit and figure out how some of the pathfinder's trickier abilities work and act accordingly around them.
yixuan's biggest hurdles to overcome i think are probably gonna be the madness manip and the attack reflection. those are probably gonna be reaaally tricky to get around, and honestly i think it's those two abilities alone that could probably net pathfinder the win. not gonna cast my vote just yet, but i did wanna at least lay out some of the stuff yixuan can do for those less informed about her