Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13-inch baking pan.
Stir yellow cake mix, 1 cup water, vegetable oil, and eggs in a mixing bowl until moistened; beat with a mixer on medium speed for 2 minutes. Pour batter into prepared baking pan.
Bake cake in the preheated oven until lightly browned and a toothpick inserted into the center comes out clean, about 35 minutes. Cool completely on a wire rack. Poke holes about 1 inch apart all over the cake with a fork.
Dissolve strawberry gelatin in boiling water in a bowl and pour gelatin slowly over the cake, letting gelatin seep into holes. Refrigerate cake until gelatin sets, about 1 hour. Transfer cake to a serving platter and cut in half horizontally.
Mix instant vanilla pudding mix with milk in a bowl and whisk until thickened, about 2 minutes; stir in 1/2 cup blueberries. Spread blueberry filling onto bottom of cake and place top of cake over the filling. Spread 2 cups whipped topping smoothly over top and sides of cake and arrange 1/2 cup blueberries in a square in the upper left corner of the cake for stars. Arrange alternating layers of strawberries and miniature marshmallows into horizontal red and white stripes.