Too many variables there to get an accurate number on the punt - down, distance, time, TOs etc. all factor in into it. The skill of the individual kicker would dictate the success rate of the FG. The average conversating rate in college football of a 4th and 8 is 20-30% but that's an average. This would be against the #1 defense in college football, so it's likely around half that number. Plus we hadn't exactly had much success throwing the ball and it was too long to try to make it on the ground.
Just spit balling this is what I would come up with:
Convert 4th and 8, kick field goal succssfully on that possession - 10%
Punt, hold, get ball back on your 30 =/- 10 YL drive 40 yards, kick a FG - 15%
Jacob Kauwer kick a 64 yard FG now - 25%
The upside to the kick is it has the highest probability of success. It's only one event that is doable and doesn't depend on a multiple of things occurring like the other two. But the downside is UGA get's the ball back with a lot of time on the clock. So pick your poison. Unfortunately the coaches didn't have the time luxury to go through a lengthy analysis so the punt was probably as good of an option as any.