Is Xin really strong right now?

He snowballs VERY well. And new jungle is completely set up to get that snowball started. So yes.

In my opinion he's so hard to fight against because of how tanky he is and how much life steal he has.

He's not strong at all, he's just easier to play. Therefore, in low elo where nobody is really good at the game, the easier champs seem stronger.

let me guess. CoC

I think he's super weak. In lane he's not actually that hard to outtrade/outright zone out. In jungle, he can be sometimes a bit scary if fed, has ok clear, but one single CC and his ganks are useless. He doesn't have any defensive scaling and he's extremely kiteable, so his lategame teamfighting is very poor ; and as for splitpushing, some champions just outscale him.

He is very strong early and mid game, but late game he's more like trundle in the fact that he wants to kill 3 turrets while you fight the rest of his team elsewhere