It could happen, but I think it's extremely unlikely. Even if Putin was to give the order, there's a very high chance this order would be disobeyed. Even if his subordinates fear that he will kill them, they are also highly likely to die if a nuclear war happens. Almost anyone in that situation would do anything to avoid total destruction of the planet.

But if it did happen, I'm done. I wouldn't hang around to see what happens. There's no way I would even bother trying to survive a nuclear winter.