Bring first 5 ingredients to a boil in a large stockpot; cover, reduce heat, and simmer 1 hour. Remove chicken, reserving broth. Skin, bone, and coarsely chop chicken; set aside. Pour broth through a wire-mesh strainer into a large bowl, discarding solids. Measure 1 gallon broth, and return to stockpot. Add sausage and next 5 ingredients; simmer, stirring occasionally, 1 hour.
Heat oil in a heavy skillet over medium heat; gradually whisk in flour, and cook, whisking constantly, until flour is a dark caramel color (about 20 minutes). Stir into sausage mixture, and simmer, stirring occasionally, 1 hour. Stir in chicken, salt, and red and black pepper; simmer, stirring occasionally, 45 minutes. Skim off fat.
Stir in green onions and parsley; simmer, stirring occasionally, 10 minutes. Remove from heat, and stir in filé powder. Serve over hot cooked rice with hot sauce, if desired.