Red cross records are the most reliable that survived. As for logostics it comes down to a couple factors. Europe at the time had a estimated Jewish population of two million. It would of taken modern cremation technology over a hundred years to process that many bodies given the numbers they had at the camps. The amount of resources to move never mind capture six million people would have drained them of man power to the point they would be unable to properly fight a war.
I believe it happened but I side with the historical evidence over a news paper article