My uneducated guess would be it would depend what was removed in the breast reduction. Milk glands are throughout the breast and will certainly still produce milk, even if there are less than there may have been initially. But that would very much depend on how your procedure went.

It's worth bearing in mind though, that supply also depends on demand, so the milk being removed from the body would be replaced. Women successfully bf twins (so effectively one baby per breast) or with only one breast, so a reduced number of milk ducts won't necessarily mean your baby won't get enough milk. I couldn't see why at the very least you couldn't try and at least partially bf. Every bit of bm is good!