Putin'll do peace talks and cease-fires right now only to buy time for resupplying his main army on the road to Kyiv. The Ukrainians need to keep that army isolated and unsupplied during any negotiations. It's hostage and potentially a huge source of Ukrainian weaponry.
Meanwhile, the West should keep arming the Ukrainian army with NLAWs, Javelins and Stingers, as well as any amount of small weapons. Ukraine must be a porcupine to Russia's bear. The fog of war and all, but the impression I get is that Ukraine is doing not only a brave but a brilliant job, perhaps with informational assistance from NATO (along with weaponry).
No mediation will produce a peaceful outcome in the long term with the liar Putin in charge of Russia. But if he loses his army in the sticky mud of the plains of Ukraine, then he will surely be removed from office by his generals. They must be screaming at his crazy leadership.