The grapevine says that independent sex workers are struggling as a result of the Online Safety Act. Unless the law has significantly reduced the tendency for UK people to engage with internet porn (which I doubt), then yes, PornHub is benefiting from this law.
Independent sex workers upload their content on websites that are affected by the OSA, like PornHub and OnlyFans, this is why they are struggling.
A lot of PornHub's content comes from independants, not big studios.