Place the pineapple in a large bowl; gently fold in bananas. Place cake cubes in a 13x9-in. dish. Spoon fruit over cake.
In another large bowl, whisk milk and pudding mixes for 2 minutes. Let stand for 2 minutes or until soft-set. Spread over fruit. Carefully spread whipped topping over pudding. Sprinkle with pecans. Cover and refrigerate for at least 2 hours before serving.