The distribution will matter very much to Labour, or at least it should. It's what's put them in such an awkward position over brexit.
I'm making no assertions whatsoever as to the rights or wrongs of Corbyn's behaviour on this issue, but the briefest look at the numbers shows that 'blaming' brexit purely on tory voters is a very long way short of the full story.
In terms of a General Election, yes it makes things awkward for Labour (the distribution of leave/remain votes). But the referendum was one person, one vote. So all that matters is the overall number and yougov have polled it. It is as clear as day that Cameron and Osborne did not persuade their own voters to vote with them, that's the crux of Brexit. Like I said, compare the voting splits of Labour and Lib Dem voters and it shows that Corbyn (and the Labour Party as a whole) did a reasonable job of taking their voters along with their side of the vote.
The failure of the Remain campaign lies with Cameron and Osborne. Their own voting bloc (people who voted Tory in 2015) told them to go phuck themselves.