In a large skillet, heat olive oil over medium-high heat. Add chicken pieces and cook until lightly browned, about 4-5 minutes. Transfer chicken to the slow cooker.
Add sliced smoked turkey sausage to the skillet and cook for 2-3 minutes until browned. Transfer sausage to the slow cooker.
Add chopped onion, green bell pepper, celery, and garlic to the skillet. Cook, stirring occasionally, until vegetables are softened, about 5 minutes.
In a separate small saucepan, heat vegetable oil over medium heat. Gradually whisk in the flour and cook, whisking constantly, until the roux is medium brown, about 5-7 minutes. Remove from heat.
Add the cooked vegetables and roux to the slow cooker with the chicken and sausage.
Pour in chicken broth and diced tomatoes with their juice. Stir in Creole seasoning, dried thyme, bay leaves, smoked paprika, and cayenne pepper.
Cover and cook on low for 6 hours, stirring occasionally if possible.
About 30 minutes before serving, stir in the sliced okra. Continue cooking until okra is tender.
Remove bay leaves. Stir in chopped parsley and green onions. Season with salt and freshly ground black pepper to taste.
Serve gumbo hot over cooked white rice.