At best you’re going to get some generically anonymous bot pretending to be human, that has limited reach because they don’t actually exist in the real world. Much of the media influence game involves podcasts, events, interviews, and a host of other things that can’t be faked.
I just don’t really see what scenario the doomsayers are imagining here. An entire media sphere of AIs that somehow shift public opinion without existing or interacting with the real media world? The practicalities don’t make sense.