It turns out I had excellent position for this game. I started out with 4 scis the first turn and 4 cols the second. I sent two each way, running into single scis from Gate Keeper in 20,21 (that jump was open to start) and Ft. Mexia. I ran into two of Gate Keeper's cols in Ft. Bend the next turn, killing off both of my southern scis. My lone northern sci continued to explore while I tricked with Home World and the four adjacent planets.
When I saw how long the chain going up north was I immediately built 5 BR-2 cols and a BR-2 engineer to close that gate. That was the key to the game...Ft. Stockton was as close to him as it was to me, and if he had managed to grab that planet I would have been doomed.
I then focused on stargating ships south to pressure Gate Keeper. He couldn't see what I had coming, so I easily killed his col in Ft. Mexia, colonized it, and moved east. From there it was simply a matter of using my econ advantage (9-4 at this point) to keep more ships on the front than he could. I kept a constant barrage of cols coming to further fuel my econ and provide stargate bases one jump closer. Gate Keeper had a 13 ship fleet hiden east of his Home World on the final turn, but it wasn't enough to stop my fleets from nuking.