I think his contribution to getting Brexit through was minor at best.
Cameron didn't call the referendum because of Farage but because of the anti-EU faction in his own party - a faction that has been a thorn in the side of the Conservative Party since at least the early 90's. I think Boris Johnson and Dominic Cummings played a much bigger part in swinging the vote than Farage.
In this election, the Reform Party will almost certainly do nothing more than split the Tory vote even with Farage in charge.
And yet for tears Farage was the one clear voice on the subject because he could not being attached to the Tory Party, be monomaniacal about it, and sound not just Barkingside mad right wing. The part of the Tory Party that Cameron was trying to appease was emboldened by having the successes of UKIP, in particular in the 2014 EU elections, something that would not have happened without Farage.
The bulk of the support for Brexit had been built up over those years, long before Cumming and Johnson were heard of, at least not on the side of Brexit.