How is China playing this?
a) Observing carefully as how the West is playing this crisis, how far they are willing to go when
China invades Taiwan Russia invades Ukraine. How powerful is the response, how far is the West willing to go.
b) Keeping a distance from both sides, but not "the same distance" from both sides:
China criticized the Washington's response on Wednesday, saying the new US sanctions amounted to throwing "fuel on the fire" and were "irresponsible and immoral."
In a joint statement, Russia and China called on NATO to "ideologized approaches of the Cold War" and "respect the diversity of civilizational and cultural-historical patterns" in other countries.
As you can see, China is nothing but happy about this, as they are watching two potential enemies erode themselves and testing their strength. Lots of lessons will be learnt on the handling of this crisis and I would not say that Europe and Democracies are playing a great role in terms of intimidation, yet at least is managing to stay reasonably united.
China is the ideological ally of Russia and even though it is not going to take sides in an arms conflict, internally we all know it is going to support Russia, in Global geopolitics if you want to compete against the USA, Russia, and China have to stay together at least for next 30-40 years until China becomes a superpower equivalent to the west. Secondly as you mentioned supporting Russia's cause is going to be rewarding for China as well, because if Russia can do this to Ukraine, China can also do the same to Taiwan and it's other regions and west would be just a mute spectator just like they would be in this case.