In a bowl, combine olive oil, garlic powder, onion powder, paprika, oregano, salt, and pepper. Add the diced chicken and marinate for at least 30 minutes.
Heat a skillet over medium heat and cook the marinated chicken until fully cooked, about 7-10 minutes.
In serving bowls, layer the cooked rice or quinoa as the base.
Top the rice with the cooked chicken, cherry tomatoes, cucumber, and red onion.
Drizzle tzatziki sauce over the top and garnish with fresh parsley.
Serve immediately and enjoy your Chicken Gyro Bowls!