In what way specifically? I think the only thing thats strongly her is her fashion sense and persona, from what I know she doesnt have any writing, producing credits and the 777 tour seemed like she just goes along with the flow and may have a say or 2 but nothing to where it feels like an empire she built (Madonna, Beyonce)
Rihanna may not be at the heart of every single track she releases, but she definitely decides the overall direction of her career, logistically and sonically. As well as the truly core things like the image and timings of her eras. It makes me laugh when people think she is some kind of cash cow who just gets prodded with some kind of metaphorical electrocuting fork and forced to make a new album. She makes music because she wants to.
She may be in control of her image but that's about it....I can't imagine her getting much work done as much as she parties, smokes and plays on the internet