Apparently there is a sizable number of Chinese XMPP users these days.
Probably because XMPP via HTTP is something that looks a lot like web browsing (as long as there are no calls), which should make it easy to keep up connections to servers that are not censored. I myself know some that have quite a few channels named something in Chinese, but I won't mention it here to not make it easier to find for the censors.
I've heard rumors that XMPP mostly works in China, but I cannot verify that. If anyone here uses XMPP in China, I'd be interested in a reply.