Preheat oven to 350°F. In a large mixing bowl, combine yellow cake mix, pumpkin puree, cinnamon, nutmeg, vegetable oil, and eggs. Mix until smooth.
Pour batter into a greased 9x13-inch baking pan and bake for 30-35 minutes. Check for doneness with a toothpick.
Let the cake cool for 10 minutes. Poke holes in the top of the cake with a fork.
Mix sweetened condensed milk and caramel sauce in a bowl. Pour over the cake, allowing it to seep into the holes.
Spread whipped topping over the cake and sprinkle with toffee bits and pecans. Refrigerate for at least 2 hours before serving.