Gill joined The Cobblers on a one month loan deal in August and that finishes after they play their 2nd Division game against Bristol City on Friday night.
He has been a regular for Northampton during that time and has impressed their boss, former Blues player, Kevan Broadhurst.
The Cobblers manager said: "I think Jerry's enjoying his football and I am enjoying having him at the club because he's a terrific professional."