1.Itch.io BAN chinese IP, not China ban Itch.io
From the perspective of game developers here, it doesn’t matter who is blocking who. All that matters is if Chinese people can see the games. Why would you anybody put Chinese-language games on a site that blocks Chinese gamers?
That said, I seriously doubt that Itch bans Chinese IPs, but I doubt even more that China doesn’t ban Itch. Because Itch is full of things that the Chinese government finds offensive. Heck, it’s full of things I find offensive. There may even be some overlap! If China doesn’t ban Itch, that’s probably a matter of oversight, not of policy.
(For the record: I would love to add Chinese translations to my games, but my Chinese isn’t nearly good enough to make the translation myself, and I can’t really afford to hire a good translator, plus an independent editor to verify the translation, at the moment.)