Heat the olive oil in a large pot over medium heat. Add the ground turkey and cook until browned, breaking it up with a spoon as it cooks.
Add the diced onion and minced garlic to the pot. Cook for 3 to 4 minutes until the onion softens.
Stir in the chili powder, cumin, cinnamon, salt, and black pepper. Cook for 1 minute to toast the spices.
Pour in the pumpkin puree, diced tomatoes, black beans, and chicken broth. Stir everything together until well combined.
Bring the mixture to a simmer, then reduce the heat to low. Cover and cook for 20 minutes, stirring occasionally.
Ladle the chili into bowls and top each serving with sliced avocado.