Stalin did not orchestrate a genocide. Many Nazis died, and many soldiers of the Red Army, but to call this genocide is ludicrous. In addition, there was a famine that has been claimed to have been targeted at Ukraine.

The evidence for this is contested at best. Finally, there is the gulag situation. Gulags (work camps) are of very questionable moral defensibility, but to call them genocide is a stretch. First, they were not targeting a racial group, but a class in society called kulaks.

Kulaks were basically an agricultural landlord class that hoarded and burned grain when the state tried to take it to feed their people, which did not cause the famine mentioned above but made it far worse. Some political prisoners also went to the gulags, which is again questionable, but not genocide.

Second, the number of people that went through the gulags was very variable by year, and at almost all times significantly lower as a percentage of population than other prison systems, such as the modern US's, and the survival rate was fairly high for work camps, although again, variable. The gulags were a penal system, one that is highly suspect, but definitively not a genocide.