there is a tiny, tiny fraction of the chinese industry used for military production. in a true national crisis, such as a loss of the 90% of the airforce with another power now invading, its would take one hell of an incompetent leadership to not bring in the total sum(as much as possible) of the nation industrial power into play. such brainless leadership might be possible in india(with its total ammo supply lasting only 15 days- mostly imported), but china plans better than that, in fact china would likely build up spares/raw materials(which it already has) prior to the start of any taiwan scenario. in 3 months it might not be able to replace everything, but it could certainly bring into enough to take on the IAF. don't forget, it doesn't have to be a 1 on 1 fight vs the IAF. the PLAAF straight up has the generational advantage, even just producing 12-24 j-20s would exert huge pressure since india doesn't even have 5th gens.
and just to be clear, i don't believe for a minute that india could even take much advantage to start with, as a taiwan scenario still leaves the vast majority of the PLAGF untouched with most of its armor and anti air.