Gill appeared in 10 games with the Toronto Maple Leafs in the 1984–85 season, scoring a goal and recording 13 penalty minutes.
Gill spent most of the 1985–86 season with the Maple Leafs' American Hockey League (AHL) affiliate, the St. Catharines Saints, and scored eight goals and 33 points in 58 games.
Gill appeared in a playoff game for Toronto, going pointless as the Leafs lost to the St. Louis Blues in the Norris Division final.
He played in 11 games with the Leafs' newly relocated AHL team, the Newmarket Saints in the 1986-87 season, scoring a goal and nine points.
In 13 playoff games, Gill had two goals and four points, as the Leafs lost to the Detroit Red Wings in the Norris Division final.
Gill appeared in 65 games with Toronto, scoring eight goals and 25 points, while registering 131 penalty minutes, the second-highest total on the team.
Injuries limited Gill to 59 games during the 1988–89 NHL season, however, he scored 11 goals and 25 points, as the Leafs failed to qualify for the playoffs.
Gill had a solid showing in the playoffs, earning three assists in five games, as the Leafs lost to the Blues in the first round.
In 1991-92, Gill stayed healthy again, appearing in 74 games, scoring two goals and 17 points, however, the rebuilding Leafs missed the playoffs for the third time in four seasons.
In 21 playoff games, Gill had a goal and 11 points, as the Leafs lost to the Los Angeles Kings in the Campbell Conference finals.
In 18 games in the playoffs, Gill chipped in with a goal and six points, as Toronto made the Western Conference finals, where they lost to the Vancouver Canucks.
Gill was named as captain of the San Jose Sharks after the team acquired him from the Toronto Maple Leafs.
With the Sharks needing scoring help for their playoff pursuit, the team traded Gill to the St. Louis Blues for Joe Murphy on March 24, 1998.
In the playoffs, Gill had two goals and four points in 10 games, but the Blues lost to the Detroit Red Wings in the second round.
He appeared in two playoff games with the Red Wings, recording one point as Detroit lost to the Colorado Avalanche in the second round.
His stay with Phoenix was short, as on March 13, 2000, the Coyotes traded Gill back to the Red Wings for Philippe Audet.
In the playoffs, Gill had no points in five games, as Detroit lost to the Los Angeles Kings in the first round.
The Frontenacs faced the Peterborough Petes in the opening round of the playoffs, and took a 3–0 series lead, however, the club then lost their next four games to be knocked out of the post-season.
In the post-season, the Attack swept the London Knights in the first round of the playoffs before the club lost to the Sault Ste.