China is not able to control bitcoin, it is impossible to do so. It is possible, that Chinese people can have on their wallets, the biggest amount of bitcoins, because of the population.
is there already a research about the biggest user is china ?, I think china itself will not be able to control bitcoin, indeed in 2017 china like playing bitcoin prices with news, but in 2020, China cant control with news! this is pure bullish trend and not bubble