Drain tomatoes, reserving 2/3 cup juice. Drain artichoke hearts, reserving 3/4 cup marinade; chop artichokes.
In a Dutch oven, heat oil over medium-high heat. Add onions, herbs, garlic and pepper flakes; cook and stir until onion is tender, 4-5 minutes. Stir in tomatoes and reserved tomato juice and artichoke marinade; bring to a boil. Reduce heat; simmer, uncovered, until slightly thickened, 10-12 minutes. Meanwhile, cook tortellini according to package directions.
Drain tortellini; add to tomato mixture. Gently stir in olives, salt and artichoke hearts; heat through. Sprinkle with cheese.