They've had to before, Afghanistan comes to mind. Without a doubt Putin has painted himself into a corner if he can't pull this off, well frankly, yesterday. The question is if he can get out of the corner, before he can't get out of the corner. Doesn't look like he got out of the corner overnight, and depending on how true the scavenging stories are about the tankers, fuel, and food, he may already be stuck in that corner.
He got into this thinking he couldn't lose, now another bad day or two and he may very well be losing whether he wants to admit it or not. If he's not actively seeking a way out by the end of the day Monday, then his strategic stupidity will near Hitler-esq levels. Either way, he's damaged the Russian's ability to project power significantly for generations with just how badly this has gone so far. He'll still have nukes and I'm sure if anyone wants to invade Russia, it won't go well, but as far as a front line superpower any longer, after this fiasco, uh no.....