They are not "currently winning". By any objective measure, the war on the ground is currently a stalement.

Only problem is that in the long term -- stalemates never work out for the occupiers.

In Russia's case: If the situation continues as it does, and moving at the glacial pace that it does, and draining 10 percent of its GDP every year -- they will ultimately have to give up on their optional neocolonial adventure, pick up their toys and go home.