You can, but not all tables can see it, so if you're really set on viewing them over dinner, be sure and arrive early for your PS time and request a view when checking in. Not all window seats overlook it either, so be sure and tell them you want to see Wishes.
We sat behind the firepit, there are a lot of tables behind there, and you could not see it. You are welcome to walk around the restaurant and view it, but there is a step down in the restaurant and you have to bend over for 14 minutes and it just isn't worth it. I lasted 3 minutes before my back was screaming for me to stop, not to mention the shrimp were calling my name back on my plate. The tables around us went on like nothing was going on, waiters still brought food, etc.
It's not the best view, but has the potential to be "icing on the cake" when dining there. I would make a PS at least an hour before the show and arrive even before that and be prepared to wait some.
If the show ends up being too late for your meal (like 10pm or something), you can dine there first and then head to the Poly beach and stand on the beach to view it, or even hop the monorail back to view them from Main St - which is the best view in all the World!
You'll love 'Ohana's, it's a must eat for us now!