While the movement of segments working class votes from Labour to UKIP is occurring, I doubt that’s Corbyn’s basis for it. He’s apparently held the opinion that the 1984 miner’s strike remains the defining event of modern Labour and that mines should be reopened since the days when UKIP was still a fringe party. (I’m basing this on comments from a local journalist who lived in Corbyn’s constituency over a decade ago.)
That said, somebody may have gotten across to him that it’s a bad idea, as he’s since said that his most recent comments on the matter were misinterpreted.