Looks like Maxim Gorky to me.... Also see his photo here, where he is older and even has a similar hat on him.

Edit: yep that's him, I've found the exact bust as you have at an auction here: http://ay.by/lot/byust-maksim-gorkij-5010381149.html

It’s almost certainly Maxim Gorky, probably the most famous author and playwright (in his own time at least) of the late Tsarist and early Soviet period. An early supporter of the Bolsheviks, he was somewhat disillusioned by the 1917 Revolution and had a deeply ambivalent relationship with the Soviet regime. Nonetheless, despite spending much of the 1920s in living abroad, Gorky was a major cultural figure in Russia and held up an icon of the state-approved literature.

Most of my knowledge of Gorky comes from his interactions with the Soviet regime. I’m sure that someone else here can provide more details to do the man himself justice.