It may be a difficult lawsuit. Pornhub is a publisher, not a platform, so they are responsible for content on their sites. If Girls Do Porn lied to Pornhub while becoming a partner, then that could shield them from liability. The fact that pornhub did not remove videos while in litigation isn't necessarily a problem, as it was just litigation.
These girls may have a hard time winning
I don't agree. It's an out-and-out violation of a contract.
I agree that they were stupidly naïve, but that isn't a crime. The producer should be liable for basic damages, at least to the extent that they've profited from the video, as well as damages paid to the the girls for mental anguish.
At bare minimum, sure profits from the videos should be suable. Pornhub just may not be liable for other damages if they can prove that Girls Do Porn lied to them about the nature of their content. If there is proof that they have no process in place for verifying a partner by say interviewing actors, then certainly they should be held liable, which seems to be the case. That gets to some gray area tho because that could affect every internet company in existance
I hope they all win.