There isn't artificial light on the savanna. That would be disruptive to the animals. The Animal Kingdom Lodge does have a special program where you can view the savanna through night vision binoculars, but they're not available in the restaurant.
You can't see them once the sun goes down because there isn't any light on the savanna and the windows reflect inward. The only animals you'll be able to see are the two-legged kind that are dining in the restaurant.
I've only been to Sanaa once, when it was dark, so my table near the windows was not a factor for me. But I really did enjoy the food and would go back.