“RuZZia can produce about 200 tanks per year.”
They are building two new tank factories, but they will take a while to get running.
Perun (on YouTube) did an analysis of how the type of Russian tank being hit on the battlefield has changed over time. It showed that new production of T-90s was a small but relatively consistent percentage of losses, while the bulk were refurbished tanks from storage, that showed a declining trend in their capability over time. Fewer with thermal sights, growing use of older models.
It seems that they have been using the best first, and will likely have greater availability problems and declining capability, as they scrape the bottom of the barrel.
Satellite pictures of storage yards show howitzers being removed at a roughly similar rate to tanks (over half gone), but most of those left have had their barrels removed. There is likely some degree of parts stripping off the tanks in storage as well, that is less visible from space.
Foreign supply is likely the only way they could maintain their replacement rate (assuming attrition rate stays constant) through this next year.
They're also mounting Soviet navy RBU-6000 anti submarine rocket launchers as well as A-22 Orgon MRL onto MTLBs too.