I could be wrong, but paying users through advertising revenue is exactly the same business model employed by faucets. As such, I can't imagine the payouts for this being vastly better than faucets. It even says in the article "payouts are typically very small". Also, if users are embedding the images they upload directly onto forums and social media, where do the advertising revenues even come from? Surely people viewing the images would have to visit the page with the ads displayed on it for it to be profitable?
All your answers would have been answered if you had just looked at their front page. They only pay for links to the site. If you post popular images that gets thousands of views then it will be much more profitable for advertisers than if the same user is clicking reload on the same page every 15 minutes. Also, this is much more interesting to look at than just ads:
https://supload.com/B1RQtimre