A hen who is not feeling well is less likely to run away or move much at all - which can often make them easy targets for a rooster looking for someone to mate, so yes.
More importantly than if she will be bred or not, though, is considering whether you want a bird showing signs of illness in with any other birds due to the issue of communicable diseases and the risk of spreading her illness to others - as well as the issue of the stress of being an easy target not only for a rooster's attention, but also less likely to move away from any other birds who decide to take to pecking at her, etc. since stress only compounds illness and can make recovery more difficult.
Well I don't really know if she's actually sick I'm so confused with this chicken lol I posted a question yesterday it's in the injuries and illness forum I think titled sick or sad hen? Lol so if you guys read that you'll see what I mean I just checked them she hadn't come outta her little nest box yet and I reached in to pet her and she jumped outta it and went outside with Rico her rooster lol and he started chasing her and she was running away and hid back inside now she's scratching around outside and so is Rico so I don't know I put the electrolyte vitamin mix in the water I'm so confused lol
Just in case, I would keep her separate from the rooster until you do figure out if she is sick or not. Roosters can harm sick birds to the point of serious injury. So don't let the rooster mate her for now.