They aren’t going to win. Their economy started with noticeable issues and has since been obliterated. Aggression wars against a weak opponent are remarkably expensive and Ukraine has received a significant amount of support (I’d estimate around 20b so far) whereas the ruble and Russian markets (bond, equity, and a large portion of export/import) have been nuked. They are running on fumes in a war that is projected to run for quite some time.
It seems like Putin will only surrender after he's expended everything he's got, and among "everything he's got" includes several thousand nuclear missiles...
I'm sure that if they are the last man standing and all of Ukraine is turned into rubble soaked through with blood that they'll declare victory. But it won't amount to much.
Real people with power build they don't destroy. The likes of Putin only know how to kill and how to destroy.
The phrase "for Russia" seems inappropriate. You mean for Putin. And... maybe? I'm not convinced. Even Stalin had to regularly kill off the people around him to maintain power.
Or Russia wins