Im ordered to have paid 14,000 by December while in the pretrial intervention program, what will happen to me if it's not paid?state of GA, 1st time in trouble.

In Georgia, if the theft is valued at $5,000 but less than $25,000, the crime is punished as a felony and imprisonment of at least 1 year but not more than 10 years. But the judge has the discretion to punish the crime as a misdemeanor. Which is yours?
I imagine that you will serve your sentence if you don't pay. I trust that you are paying as much as you can each month until December, to better your chances, and that you have some connection to the court to work on a payment plan? If I were you I would be scrambling to find 14 relatives to borrow from.

... what will happen to me if it's not paid?...

I'm very surprised that they didn't explain that to you.