There is actually real serious money for it - India has been wanting to buy a fleet of those planes for years and is pretty frustrated with the delay. Russia still is just not capable of producing it. Too complex tech.

Specifically the 3 major components has to be of the 5th generation - body, engine and radar. The SU-57 body is pretty much there. The radar isn't there yet where it was promised and is required to be (ie. distance, number of tracked items, etc.). The worst situation is with the engine. Russia still doesn't have 5th gen "stealth" engine. What is being flown currently is "4.5" gen - a well improved 4th. You can see it clearly here https://en.wikipedia.org/wiki/File:Sukhoi_T-50_Maksimov.jpg