Heat oil in large heavy pot over medium-high heat. Add onions; cook, stirring occasionally, 7 minutes, until golden. Add garlic and chicken; cook, stirring, 6 minutes. Add paprika, salt, cumin, cinnamon and cayenne; cook 1 minute.
Add chicken broth, tomatoes and chickpeas. Bring to a boil. Lower heat to medium-low; simmer 5 minutes.
Add couscous, raisins and olives; stir to combine. Remove from heat. Cover pot; let stand 5 minutes.
To serve, fluff couscous gently with a fork. Serve with warm pita bread and garnish with lemon wedges, if desired.