My DH is about that size and it was fine for him~ By the way, I noticed on your ticker that we will be there the same time as you. We are so excited, too~
I am sure he will be fine as the above have mentioned. But I would like to add that the other night this resturant was included on unwrapped... and they did have a larger man and his wife on. He explained how they loved to sit at a table on the side because it was more comfy for him. So no matter what they will make you comfortable.
It is a pretty small space sitting in the cars but you could request a picknic table. I recommend getting the ribs! They are very lean and meaty! mmmmm
My DH is 6'2" and I am 5'11" and we've both fit into one 'car seat' before. We might have been a little short on elbow room but leg room was fine. If you have concerns there is a car that sits outside of the restaurant that is just like the cars in the restaurant. Have your DH sit in that to see how he feels and of course to take a picture.