Is BitCoin controlled by China?
Here is Blockchain.info's chart showing the current estimated distribution of the bitcoin network's hashrate.

Keep in mind: some pools are composed of many individual miners, so in the event of an attack, those individuals may simply redirect their hashpower to a different pool that is not involved in the attack.

In general, controlling the hashrate is not equivalent with 'controlling bitcoin'. If a single entity got control of 51% or more of the hashpower, then they could launch a 51% attack, meaning they could censor transactions. This is an existential threat to the network, but many developers have proposed countermeasures such as a POW change in the event such a thing ever happens.