Preheat oven to 325°F and generously grease and flour a 10 to 12-cup Bundt pan, making sure to coat all crevices.
In a large mixing bowl, combine cake mix, pudding mix (if using), vegetable oil, ¾ cup pineapple juice, eggs, and 1 teaspoon vanilla. Beat with electric mixer on medium speed for 2 minutes until smooth.
Pour batter into prepared bundt pan and spread evenly. Bake for 30 to 35 minutes until toothpick inserted in center comes out clean and cake begins to pull away from sides.
While cake bakes, prepare glaze by combining powdered sugar, ¾ cup pineapple juice, butter, and vanilla in small saucepan over medium-low heat. Stir until butter melts and mixture is smooth. Keep warm.
Let cake cool in pan for 10 minutes. Use skewer to poke holes all over top of cake. Slowly pour warm glaze over cake while still in pan.
Allow cake to cool completely in pan, 15 to 20 more minutes, until glaze is absorbed. Invert onto serving platter and serve at room temperature or slightly warmed.