He said that it happened, there is even a
clip of him saying in it this post. Mind you, he's only saying that it happened, not that it was a terrible thing, you could say I'm nitpicking but he's grifting turkroach so needs to say it outright or else he thinks it was a great thing.
His uncle, Cenk, back in the 1990s said that it didn't happened but later in 2016 he acknowledge that it did happened and that it was horrible.
Also, for the sake of being thorough he has denied that the Uyghur genocide is happening. He calls the concentration camps "reeducation centers".