Preheat oven to 450 degrees.
Coat a baking sheet with a little olive oil.
Arrange tilapia in a single layer on a baking sheet; season with salt, pepper and 1/2 teaspoon of cumin.
In a small bowl, combine tomatoes, olives, cilantro, oil and remaining cumin; spoon mixture over the tilapia and bake until fish flakes easily when tested with a fork (12 to 15 minutes).
Serve immediately.