Pat chicken thighs dry with a paper towel. Season with salt, pepper, 1/4 teaspoon cinnamon and 1/4 teaspoon cumin.
Heat 1 tablespoon olive oil in a Dutch oven over medium heat. Add the chicken thighs and cook until browned, 3 to 4 minutes per side. Transfer to a plate and set aside.
Add the remaining 1 tablespoon oil and onion to the pan. Cook, stirring occasionally, until the onion is softened, about 2 minutes. Add the remaining 1 teaspoon each cinnamon and cumin and cook, stirring constantly, for 30 seconds. Add tomatoes and their juice, chickpeas, broth, 2 tablespoons cilantro and orange slices; bring to a simmer, stirring with a wooden spoon to scrape up any browned bits. Return the chicken and any collected juice to the pan; cover and cook over medium-low heat until the chicken is cooked through, 5 to 10 minutes. Transfer the chicken to a clean plate.
Bring the cooking liquid back to a boil; stir in couscous and place the chicken thighs on top of the mixture. Remove from heat, cover and let stand for 5 minutes before serving. Garnish with the remaining cilantro.