I had a breast reduction when I was 18 and had dd when I was 32. Although we didn't have a successful bfing relationship, (because she was extremely premature) I was able to pump and good supply. I did take supplements and stuff, but I believe with my next baby, I will be able to bf just fine.
The truth is, she will not be able to tell until after baby is born and they give it a shot.
A great gift for her would be a book called Defining your own success
by Diana West. It is about bfing after a reduction.
You may also want to turn her on to a group on Yahoo called BFAR (breast feeding after reduction) It is an AWESOME resource.
If you have any other ?s or she wants someone to email or whatever, pm me.