Where did 200 million men come from?
China's conventional army currently stands at 2.3 million, which over the past 3 years has been reduced from 2.5 million.
Incidentally it's not much larger than the current US millitary.
As for the original question, yes china probably could invade russia on the strength of numerical supperiority and the fact it's army has been built
to fight russia for the past 50 years.
Currently the Type-99 MBT is better than anything russia is fielding and Chinese air to air missiles are also better.
Russia has better APC and SAM technology, though that depends on just how much they are willing to sell to China.