Cook the pasta according to the package directions. Drain and rinse under cold water.
Meanwhile, heat 3 tablespoons of the oil in a large skillet over medium-low heat. Add the garlic and cook until softened, about 2 minutes.
Add the capers and olives and cook for 3 minutes. Stir in the parsley and cook until wilted, about 1 minute.
Remove from heat. Add the lemon juice, pepper, and the remaining oil.
Divide the pasta among individual bowls. Top with the tuna and olive vinaigrette.