In such a scenario the one out that human writers have is to rely on word of mouth to build a dedicated base of readers that would follow their work specifically. The advantage of human writing over AI writing is the human's ability to see the bigger picture and tie threads in the story together into a larger arc that makes narrative sense. This isn't immediately visible at the start of a story, you'd have to read far enough into it to where it stops making sense. So it would indeed be hard for readers to pick out human-written stories from among the crowd, and any human writer starting off new would probably have weak numbers unless he gets lucky and strikes a cultural nerve. But once readers do find a human writer they like, then it makes sense to follow that person afterwards long term as a trustworthy source, since then you know at least that person isn't going to post slop (though they will certainly have other personal foibles you can love or hate).
And if AI gets advanced enough, or a user is skilled enough with it to eliminate the big picture problem, then maybe that skilled user of AI deserves to get more views, purely on the merit of what is produced. Here, the human's role is quality control, and a lot would depend on how well he executes it.
You could say it's a bit like doping in the Olympics, but this isn't the Olympics, there's no medals being awarded. It's more like SNL's All-Drug Olympics. Sergei can pull his arms off, people may laugh, it doesn't matter that much. But really it's more like a market that's been flooded with cheap Chinese knockoffs. Sure, they're fake, but are they just as good as the brand name product? If so, then why not buy the knockoff instead? If it's not as good, then you get what you pay for, and things will sort themselves out on those lines.
