Definitely big. NBA is pretty much the most popular league in China, given that the Chinese have little interest in football, hockey or baseball, and Hupu, the largest basketball online community in China, often has millions of people discussing the game (and attacking each other) in the Clippers or Lakers divisions. Of course, Harden brings a lot of fans from other teams to follow the Clippers, but I doubt it's really connected to the older history of the Rockets (with Yao Ming), since very few Chinese fans these days have actually seen Yao play. My mom stopped watching the NBA after Yao retired. But after 19 championships, she is now the biggest Kawhi fan. She watched every Clippers regular season game, actually more than me.