Usually if someone is working with a reputable brand they get paid €xxx for a grid post and €xxx for a story, it would explain why a smaller company like ohmyglam would use smaller bloggers like Julie and Sarah because they would be a lot cheaper than someone like facesbygrace who can charge up to €4000 for an ad on their stories.
If they have a discount code they can also earn money when someone uses that link.
I wouldn't imagine that is Julie was being paid in makeup by ohmyglam that she would have such a dirty palette, but again this is Julie we are talking about