My brother has been through probation for a couple years and was on his last stretch with communtiy control in Florida. Recently, he was pulled over after his allotted hours with a DUI. He is in county jail right now. What is the possible sentence/ jail time he could be facing?

Well first he could have his probation violated and have to go serve that original sentence. Or have to serve some jail time for the violation.
Then the issue of the DUI, depends on how many priors, most likely lose drivers license, large fine and an additoinal probation for that.