TIW is an official blackout date for Thanksgiving. From the TIW section of WDW website
- All Tables in Wonderland locations are blocked out for Mother’s Day, Easter Sunday, Independence Day, Thanksgiving Day, Christmas Eve, Christmas Day, New Year’s Eve and New Year’s Day.
I have not seen similar definitive language for DVC discounts for thanksgiving, but when we went to Crystal Palace in 2017 they said they accepted no type of discount (DVC or AP). I think they are considered membership perks and subject to change year to year and are restaurant specific.
My best guess is you will get a discount on Friday but not on Thurs.