If they can they will. However there is a possibility they won't be able to fit in another guest (and yes, even a 1 year old counts!). The bad thing is you have no way of knowing either way until you show up.
The best thing to do is to change your reservation to a party of 9 before you go. If you can't, then prepare for the worst (being told sorry, we can't seat an extra person) and hope for the best. Good luck!