according to AllEars, if their information is correct, they list AP, Disney VISA and DVC at 10% and TIW at 20% for 2018. it doesn't say if this is just the restaurant or restaurant and lounge.
I seem too recall being told “no” when I asked about the DVC or AP discount by while sitting at the lounge. Since I was solo that night, I didn’t want to sit inside; otherwise I’d make the reservation and get the discount.