Championship leader Max Verstappen scored a crucial bonus point in finishing second.
When the weekend's second race was cancelled, SVG could not be headed, with one race remaining in the championship.
Should results go his way, the 32-year-old can claim the title on Sunday.
The Brit came from 10th on the grid to pass the Dutchman with 15-laps remaining.
The Kiwi currently leads the Supercars Championship, with the Aussie his nearest rival.
The Kiwi ace was forced to start from eighth on the grid, but made up for lost time.
SVG followed home Anton De Pasquale in the first of three races this weekend.
The four-time winner admits he won't return to the starting grid at Mount Panorama.
"It's still a long way to go but it's of course looking good."
The Red Bulls of Max Verstappen and Sergio Perez start on the second row.
Van Gisbergen has extended his lead atop the 2021 driver championship standings.
The 42-year-old will represent the iconic NZ motorsport brand in the new series.
"Every Formula One Grand Prix promoter wants to hold a sprint race."
The Kiwi won his 12th race of the season, taking the chequered flag in Sydney.
The Red Bull driver holds a 12-point championship lead with five races to go this season.
Courtney Duncan has had to contend with injuries and being unable to return home after the death of her grandfather in July.
The Dutchman powered home to beat Hamilton by less than 0.4 seconds to gain the advantage for Monday's (NZ time) feature race in Austin.
The 25-year-old only needed one of two races to wrap up the crown.
The two are locked in a razor-close battle for the 2021 championship.
The 24-year-old won't feature in the series' fourth season.
