Preheat the oven to 350. Lightly mist a 12 cup bundt pan with vegetable oil spray, then dust with flour. Shake out excess flour.
Place cake mix, orange juice, oil, sugar, vanilla and eggs in large mixing bowl. Blend with mixer on low speed for 1 minute. Stop machine and scrape down sides of bowl. Increase mixer speed to medium and beat 2 minutes more, scraping sides again if needed. The batter should look thick and well blended. Pour the batter into the prepared pan and place in the oven.
Bake the cake until it's golden brown and just starts to pull away from the sides of the pan, 45-47 minutes. Remove pan from oven and place on wire rack to cool for 20 minutes. Run a long, sharp knife around the edge of the cake and invert it onto a rack to cool completely, 30 minutes more.
Meanwhile, prepare the glaze. Combine the confectioners sugar, fresh orange juice, and orange zest in a small bowl and stir until smooth. Place the cake on a platter and pour the glaze over the top, letting it drizzle down the sides and into the center. Let the glze set for a few minutes before slicing.