They already have 90 J20's and the number is growing. Also 200 J16's online..
Atleast the wiki says so but the 90 seems tk high a number at best it would be in the 60-70's realistically..I doubt they have 90. They seem to have stopped at 50 and plan to build up numbers with the J-20B instead.
The Russians are causing the Chinese trouble with supplies of the AL-31. It appears they are trying to force the Chinese to buy more Su-35s in exchange for more engines. So the Chinese are working on using indigenous engines. And their next J-10 iteration called J-10D is expected to carry a new engine. The J-11s have already transitioned to Chinese engines.
The J-20B is expected to see a modified WS-10 whereas the J-20C is expected to have a brand new next gen engine.