Craig Westcarr's early goal had given Chesterfield the advantage at Priestfield on Saturday but the prolific Danny Kedwell headed in off the crossbar to level matters for the Gills.
Westcarr was then sent off for two bookings in the last 10 minutes.
Exeter climbed to second after easily disposing of a disappointing Burton side in an easy 3-0 victory at St James Park.
Jamie Cureton gave the hosts the lead after only 18 minutes and the score was doubled by Arron Davies four minutes from the break with John O'Flynn wrapping it up.
Dean Smalley's missed penalty proved costly as Oxford's winning start to the season came to an end with a 3-1 defeat at York.
Michael Coulson fired York into a first-minute lead before Smalley's penalty was saved by City goalkeeper Michael Ingham.
Ashley Chambers doubled the lead before Patrick McLaughlin sealed the win after earlier putting through his own net.
Accrington moved up to fourth following a comprehensive 3-0 victory at Cheltenham.
The visitors always had the upper hand from the moment Padraig Amond gave them the lead with George Miller and Romuald Boco adding further goals.
Rotherham eased past Bradford 4-0 to keep their 100% record at the New York Stadium.
Michael O'Connor's 30-yard effort had the hosts in front after just 51 seconds, before former Bantam Gareth Evans volleyed home to double the Millers' advantage. Ben Pringle's strike then put the result beyond doubt 10 minutes later, with Evans grabbing a second late on.
Morecambe cruised to a 3-0 victory at Bristol Rovers thanks to three second-half goals in the space of 10 minutes.
Gary McDonald broke the deadlock with a low finish shortly after the break. Nick Fenton doubled the lead with a right-footed volley from a narrow angle before Kevin Ellison waltzed through a wide open defence.
Fleetwood hammered Aldershot 4-1 with a brace from Junior Brown and Steve McNulty and Andy Mangan on target.
Rochdale bagged two first-half goals through Ashley Grimes and Dele Adebola to register a 2-0 win against Barnet.
Rhys Griffiths scored on his debut as Plymouth Argyle secured their first win of the season with a 3-2 triumph over Northampton.
And Southend did likewise, with loanee Britt Assombalonga netting the only goal of their home clash with Wycombe.