Simple question: do you attribute all preventable or violent deaths under capitalism to the ideology of capitalism? If yes you probably have over billions of deaths since the ~1600s.
Simple answer: I would count violent purges and death camps, mass executions, deliberate impositions of famine, deaths due to mass confiscation of property, gulag deaths, etc. Those are active killings of people.
Besides, even if the stats are exaggerated by factor of 10, communism still winds up being terrible.