AUS has one commuter gate and 24 with jetways for a total of 25. And yes, we have a Gate 13.
Here's another bit of gate number trivia. Austin's new Bergstrom International Airport was supposed to have opened with 20 gates on May 2, 1999. Midway through construction of the terminal due to airline demand, the city council voted to go ahead and open with 25 and five additional gates were added on to the west concourse. The additional gates were actually completed right before the scheduled opening date, but the airlines wanted to have more time to have their employees get familiar with the facility so the airport's opening was delayed three weeks until May 23, 1999.
The next phase will be a 5 gate expansion on the east concourse, and then later the two piers going out from the central terminal.
If you look real close at the airport model (pictured below) that's upstairs on the mezzanine opposite Gate 7, the model only shows the 20 gates the airport was supposed to originally have opened with.