There is a fascinating article in the Financial Times about how Brexit is affecting the churn of votes between the 2015 and 2017 general elections, which includes this graphic based on YouGov polling evidence.
Basically this analysis suggests that the Conservatives are doing well because the party is -
1) holding almost all their 2015 support and gaining nearly half of those who voted for other parties in 2015 among those the FT calls "Hard Leavers" - their term for people who voted to leave in 2016 and still think that is the right decision - and
2) holding onto 91% of those people who voted Conservative in 2015 and are "Re-Leavers" e.g. people who voted Remain but accept the result of the referendum. (The Conservatives are also making modest gains from "Re-Leavers" who voted for other parties
Among "hard remainers" - those who voted to remain and think the referendum should be overturned - Labour are holding on to most of their support and the Lib/Dems are making small gains. A couple of percentage points of Conservative support have gone to the Lib/Dems from this group - which may cause a few difficulties for Conservative candidates in those Con v Lib/Dem marginal seats which heavily voted Remain - but not nearly enough to offset the support the Conservatives have gained.
In West Cumbria it is my impression that Labour is even losing more of their "Hard Remain" support as well because of the Corbyn factor - e.g. his past comments on Trident and Nuclear power have gone down particularly badly in a county where two of the biggest employers are the BAE yards in Barrow and the nuclear industry.
Obviously the analysis above excludes "soft leavers" who voted Leave in 2016 but regret it, and all those who didn't vote in 2015 or in the referendum - but that is not much of an issue as the former are only a couple of percentage points of the electorate, and the latter probably won't vote in the 2017 General Election either.
And despite the Corbynista fantasy that they can win an election by getting non-voters to turn out and vote Labour, what evidence we have suggests that if you can persuade those who normally do not vote to turn out they are not necessarily all aligned with the Labour party.
The problem for Neil Kinnock when he was Labour party leader and proclaimed "The sun's out and so are the Tories" was that his campaign got the "Tories out" in a rather different way than he had intended - he brought millions of Tories out to vote against him!
Nothing should be taken for granted and the only poll that counts is the one on 8th June. A big win for Theresa May looks very possible but a lot could happen between now and the election and it will all depend on who turns out on the day.