Prepare and bake marble cake as directed on the box.
Poke holes in the cooled cake with a fork. Dissolve the strawberry gelatin in 1 cup boiling water. Pour the gelatin over the cake, and refrigerate for 2 1/2 hours.
Combine whipped topping, vanilla pudding, milk, and vanilla in a mixing bowl. Mix with an electric mixer on high speed for 3 to 5 minutes, until frosting is thick enough for spreading. Frost the cake, and serve. Store any leftovers in the refrigerator.