The pair claimed victory by a meagre 2.1 seconds despite engine issues and multiple punctures across the four-day event.
The Australians were leading at the mid-way point on Friday but fell to sixth by the end of the day owing to those issues, 43.6 seconds in arrears of leader Petr Borodin
They fell even further to eighth after another puncture but began to work their way up the leaderboard and benefitted from their rivals suffering their own issues.
Going into the final day, Gill and Brkic held a 19-second. That gap whittled down to just 4.2 seconds going into the last stage, which was ultimately enough to hold on.
Runner-up Turkan Ali would have won if not for a 10-second penalty for being late to timing control on stage two of the rally.
“It’s simply an amazing feeling to take the top step of the podium in our home away from home in Finland,” said Gill.
“The number of twists and turns that the weekend took showed that it was a true rollercoaster, and despite a few little setbacks, Dan and I worked hard to stay patient throughout the whole rally.
“When we had our puncture on Saturday, we knew the time loss wasn’t massive, so we kept at it, knowing that anything could happen.
“I think it was that attitude that helped us set some great times and get us back in with a chance for victory.”
Victory puts Gill in arm’s length of JWRC points leader Romet Jurgenson who failed to score points after an early incident.
Gill leapt ahead of Diego Dominguez Jr in the standings after he finished sixth.
As it stands, Gill trails Jurgenson by six points. Only the best four results from the season will count towards the title.
The season-ending Acropolis Rally in Greece on September 5-8 will pay double points.
“Winning this weekend gives us a chance in the championship,” said Gill
“It’s something we’ve been working towards all year, and we’ll leave no stone unturned in our preparations for Greece next month.”