Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.

Combine cake mix, 1 cup water, eggs, and oil in a large bowl; beat with an electric mixer on low speed until moistened. Increase speed to medium and beat for 2 minutes. Pour batter into the prepared baking dish. Bake in the preheated oven until a toothpick inserted into the center comes out clean, 21 to 26 minutes.

Poke holes all over top of cake with a fork. Combine 1 cup hot water and remaining 1 cup cold water with 1 package gelatin powder; stir until gelatin is dissolved. Pour mixture over cake. Chill in refrigerator until cool.

Stir milk, pudding mix, and remaining 1 package gelatin powder together in a large bowl until powders dissolved. Fold in whipped topping; spread over cake. Refrigerate until ready to serve.