Gill was born to a Sikh family in Punjab, India. He was educated at the University of Toronto, and holds a Master's Degree in Engineering. He works as a Chemical Engineer in private life, and has invented environmentally-friendly products such as "The Alternative Bleach", offered by the President's Choice company. He started a private firm called Genpro Canada Ltd in 1990. Gill has been a director of the Pharmaceutical Manufacturers of Canada, and is a member of the Association of Professional Engineers of Ontario. He was also a founding member of the Malton Cougars Soccer Club.
In 1982, he ran for a seat on Peel District School Board, but lost.
In the 1999 provincial election, Gill ran for the Ontario Progressive Conservatives in the riding of Bramalea--Gore--Malton--Springdale, which has a large Indian-Canadian community. The riding is located in the "905 region", which at the time was a primary base of support for the Ontario Tories. Gill was elected, defeating Liberal Dave Toor by about 4,000 votes, and became one of the few representatives of an ethnic minority group in the PC caucus.
The Liberal Party made strong gains in the 905 area in the 2003 provincial election, and Gill lost his seat to Liberal candidate Kuldip Singh Kular by almost 4,000 votes, following a bitter and divisive campaign.
In the Canadian general election of 2004, Gill ran as a candidate of the Conservative Party in the redistributed riding of Bramalea--Gore--Malton. Although this seat was actively targeted by the Conservatives, Gill lost to incumbent Liberal Gurbax Singh Malhi by 7,800 votes.
Gill announced his decision to quit politics after the election. He later reconsidered, and ran in the 2006 federal election in the riding of Mississauga—Streetsville, against Liberal incumbent Wajid Khan. He lost that contest as well, losing by about 5800 votes to Khan.