Much simple answer is that Russia doesn't have a viable air force. Air force and the navy, not tanks, lets military get things done - land troops are just to seal the results of the already won battle.

Having a viable air force requires a viable electronics industry which Russia completely lacks, and metal processing achieving much better tolerances than they shown to be capable of doing - which defines both stealth and engine performance. Sorry but there is no way to "hack" this: having a viable air force requires an advanced economy and science which only a rich country may have.