Putin is bluffing, like he always does.
He was going to cut gas and oil supplies to Europe, if we would interfere in Ukraine, but he never did. germany is delivering directly weapons to Ukraine, but Putin did not punish them.
Putin says oil and gas should be paid in Ruble starting april,1 or no deliveries anymore. Oil and gas are still flowing like before to the West. So bluff again.
Putin suggested he would take Kiev in a few days. Again bluff.
Putin said he had one of the strongest armies in the world and could destroy Europe if he would. Reality is that even a much smaller army with much less weapons resists already almost 2 months. The Russian army is a joke.
So Putin tells all the time what theoretically would happen, but practically nothing of all this happened.
Putin cannot start a nuclear war on his own. he needs other military people to start that action (authorisation and execution of the mlaunching). I think at that point several of these people, needed to start the nuclear war, will think twice as they and their family will die in just a few days. Not everybody is as lunatic as Putin. So the weakest chain in the execution of all orders can stop Putin.
Putin is gambling on the fear of the West for a nuclear war. And he uses that fear at his advantage. Just like all previous threaths. And these previous threaths confirm that most of it was bluff. Barking but not biting.