I've not been on Christmas Eve, but
this Disney Food Blog post includes info from last year and will presumably be updated. Are you looking for something "traditional" (I believe La Luce in the Bonnet Creek resort area does the traditional Feast of the Seven Fishes) or just a good meal in general that feels festive? If the latter, I'd suggest dinner at one of the resorts that goes all out for decor - maybe Citricos or Narcoossee's at Grand Floridian or Jiko at Animal Kingdom Lodge.