Fill a large pot with lightly salted water and bring to a rolling boil; stir in tortellini and return to a boil. Cook uncovered, stirring occasionally, until the tortellini float to the top and the filling is hot, 2 to 3 minutes. Drain and set aside.
Heat oil in a large skillet over medium-high heat. Add sliced sausage and saute until browned and cooked through, 5 to 7 minutes. Remove sausage to a plate and drain and discard grease from the skillet. Add mushrooms, onion, bell pepper, and garlic to the skillet. Cook and stir until vegetables have softened, 5 to 7 minutes.
Add reserved sausage and tortellini to the vegetable mixture, and pour in Alfredo sauce and olives. Stir everything together and cook over medium heat until heated through, 3 to 5 minutes.