It's obviously false, didn't you know? Stalin killed 20 billion people!
EDIT: the figures given by the government during de-stalinization detail at least 300,000 people sent to the gulags, of which more than half returned. The population figures from ukraine show 2 million affected by starvation, after the kulaks burned all their stock following Stalin's order to collectivize grain. An additional 200,000 from the purges. Quite a terrible outcome.
World War II, additionally, claimed the lives of 21 million soviets. If Stalin had killed around 30 million people, like the "Black Book of Communism" claimed, then we are talking about more than half of the Soviet Union's population gone, which would have made it impossible for it to recover. Stalin's government was terrible, but those figures are an exaggeration.
Still far away from neonazis claiming that "Stalin was worse than Hitler", however.