The duo had won the first race yesterday.
Patel and Gilbert, representing Team OD Racing, piloted their Audi R8 LMS to second with a strong performance, a press note here said.
The Indian started race two in 8th place overall and 2nd in the Silver class.
The double podium in the weekend meant they lead the standings after round one.
"Incredible! It's definitely going to take a few days for the feeling to sink in. We had our strategy in place and knew we'd be able to fight for a top five finish in race 2. Mitch did a magnificent job to fight his way up to 2nd," Patel said after the race.