Sydney Sixers captain Haddin initially sparked the big row last month when he questioned Gayle's value to the winless Thunder.
Gayle used Twitter to retaliate with a tirade the next day.
However West Indies all-rounder Bravo on Monday said both his fellow countryman and Haddin had put the disagreement behind them for the Manuka Oval match on Tuesday night - Canberra's first ever day/night match.
"We are all teammates we are all friends," the West Indies vice-captain said.
"Chris is a very easy going guy, a fun loving person.
"And I was fortunate to be led by Haddin when I played for the Sixers last year. He's a lovely guy also.
"It's something they have both put behind them."
Bravo also jumped to the defence of Gayle's form, saying he was only one innings away from being back to his devastating best.
"We all know Chris is one of the best players in the world, you can't hide that, and these conditions suit him," Bravo said, referring to Gayle's 146 off 89 balls against the PM's XI three years ago.
"I know obviously he had a bad Big Bash this year but the previous seasons he did well with the bat. I hope that people remember that and know that he's still dangerous."
Haddin was also quick to play down the row with Gayle.
"I think it will be all good," he said.
"That was about a month ago. We're here to celebrate the PM's XI. That's not in my thoughts anymore."
Haddin also said he was looking forward to playing under former Australian skipper Ricky Ponting in what is expected to be the cricket great's last international match.
"(Ponting) can be argued as one of the best players to ever play the game for Australia," he said.
"So to get the opportunity to play here under him again in the one dayer I would have been stupid to pass it up."
Haddin, who played two ODIs for Australia against Sri Lanka earlier this month while wicketkeeper Matthew Wade was being rested, said he never doubted he could still perform at the top level.
"With a bit of luck I can have a bit more of that before my career's done," he said.
Another focal point of the match will be Usman Khawaja's innings.
Khawaja, who was dumped from the ODI team after being run out for 3 in game one against Sri Lanka, will be keen to put on a big score.
Not only will a good innings put him back in the line of sight for ODI selection, but the Australian Test squad to tour India is due to be announced on Thursday.
PM's XI: Ricky Ponting (capt), Brad Haddin, Fawad Ahmed, Jono Dean, Alex Doolan, James Faulkner, Peter Handscomb, Usman Khawaja, Alister McDermott, Gurinder Sandhu, Ashton Turner, Nick Winter (12th man).
West Indies squad: Darren Sammy (capt), Dwayne Bravo (vc), Tino Best, Darren Bravo, Johnson Charles, Narsingh Deonarine, Chris Gayle, Jason Holder, Sunil Narine, Kieron Pollard, Kieran Powell, Kemar Roach, Andre Russell, Ramnaresh Sarwan, Devon Thomas.