Covert Cabal counted Russia's tank and AFV decline since the start of the war:
Russia is basically losing over 1000 tanks a year, and Russia still has over 3000 left. Sounds like they can go for another 2-3 years? Well, no, because those 3300 left are almost all in such terrible shape that they will need very extensive repairs to even function again, let alone to be of any use on the battlefield. In other words, it gets more and more difficult to replace the tanks for Russia.
The translucent lines are the total numbers as counted, while the thicker lines represent vehicles that are actually in any usable shape, and also includes vehicles that were in garages, hence why it's originally higher than what was visible at first. So yeah, not very much left that is of any use.
And here's a little breakdown of what's left, by tank type:
No more T-90, the T-80 is becoming an endangered species and barely any T-64 have come out of storage, so those are probably all junk. Which leaves Russia mostly just with T-72 and T-62, plus a few T-54/55, several of which are actually turned into BTS-4B Armored Recovery Vehicles.