Putin will not survive this. Sanctions are harming both the commoners and the oligarchs and either or both will overthrow him. That he knows this tells me that unlike Stalin he lacks self preservation instincts.
I cannot speak about the gulag. However he has purged his own citizens, such as the guy who revealed to the world his sexual proclivities.
On the other hand, how the West is doing little more than waving its finger and posting on social networks which have banned Russia already, he probably believes he can strike first, and honestly the West has done nothing to make him believe otherwise.
Also Hirohito didn't wield the real power. His generals did. Still the generals got him to stay even after the USA had told everyone that he wouldn't. Germany got a very different deal: some tried, some killed, some exiled, some forgiven and some hired by the winners. Plus Germany has had to apologize over and over while Japanese discourse still pretty much denies their own brutality. (To be entirely honest, both were supported by some in their occupied countries for their own role as enemies of my enemies).