Twitter Question: If you "reply" to someone on twitter who is NOT following you...do they even see it?

just wondering..all these celebs are asking people “what do you think of this, or do you like my hair, or how many of you…?” but when you look and see who theyre following its like 20 people out of their 15,000 people following them! so do these people just simply reply and somehow they can see it even if they are not following? thanks!!