I do believe that most go to the cruise line. The reason in that thinking is :
1) the Restaurant would be a losing proposition
2) lets say most goes to the waitstaff on average lets say a waiter in a specialty retaurant will serve approx 15-20 people per night thats only 7 - 10 couples...and lets say the fee is 30 -40 dollars that means on average a waiter and his busboy will take in on a 7 day cruise approx $4,100 - $5,600 which mean they are among the highest paid people out of most people in the United States. times those figures by the number of weeks in a year and it comes out to about $209,200 - $291,200...ABSURD. Dont believe what you hear. I am not sure if the Captain of the ship even makes $291,200 a year. That is basing a price of anywhere from 30 - 40 per person based on just 7 - 10 couples per night. The numbers speak for themselfs.
3) reason 3 is if the cruise line does not make any profit (I believe I already proved they do) then why not have this quality of food and service throughout the MDR. The reason they can't is because they would have to raise the price of the cruise, it's that simple.