At least for the moment, I can't imagine Putin agreeing to anything that would end the war aside from Ukraine surrendering. To lose would be to hand a victory to Ukraine, which would be intolerable after all of the justifications he gave to the Russian people. It would also be a victory for NATO, which would likely continue sanctions and do anything else --short of military action-- to rub his nose in his defeat.
I think it will be a war of attrition, quite possibly right to the very end. So it would be a matter of who runs out of fighting men first. And in the end, both countries will have suffered damage and losses that will take decades to recover from. Even in victory, this could spell the end of Russia as even a moderately powerful nation.