Obviously these are incredibly difficult problems to solve, and I was initially a bit sympathetic with PornHub for that reason. However, the following struck me:
While Pornhub would not tell me how many moderators it employs, I interviewed one who said that there are about 80 worldwide who work on Mindgeek sites (by comparison, Facebook told me it has 15,000 moderators). With 1.36 million new hours of video uploaded a year to Pornhub, that means that each moderator would have to review hundreds of hours of content each week.
80 moderators is so low they almost might as well not have moderators at all. And clearly they are making boatloads of money, so it's not like they can't afford them. It's an insult to victims of abuse. So is their so called "measure" of doubling the number of moderators. 2 * ~0 = ~0
Having all uploaders confirm their identities, while not a perfect measure since it could expose people who legitimately want to remain anonymous, seems like a reasonable solution. This isn't YouTube, it's a place that's exclusively populated with extremely sensitive content.
Other than that they should clearly do a lot more to algorithmically detect reposts of known abuse videos. YouTube does it with copyrighted work, there should be little to stop PornHub from doing the same. I know it's easier said than done, but they are making billions. They could invest a few hundred million into this.