Millions did not die in gulags. Gulags were not death camps and while deaths did happen, it was not the goal and if you go and check the numbers, USRR's numbers are very very different than nazi death camps.
Stalin's repressions toll, whether in Gulag camps, forced labor or mass executions, was in the millions; though not tens of millions, as americans and their mercenaries from ex Soviet republics like to tell. The conditions in Gulag camps in Stalin's time, and also quite a bit after, were horrible.
