Owen Jones on today's Guardian podcast says that Labour's internal polling ("doorstep data") suggests a 12-15 point Conservative lead.
He then qualified that by pointing out how the Tory campaign has moved from campaign stops in Labour seats they think they can win to a more defensive strategy.
The overall tone of the discussion on the yougov report was fairly negative. A clear argument that I've heard from multiple places is that Labour are winning in the cities, and in places with large numbers of former Green and Lib Dem voters, i.e. parts of the country where Labour are either already very strong or very weak. So even a bump in the polls isn't going to be an obvious help for them, on current trends. Where they appear to be weak is in the towns and villages of the country, obviously meaning the areas that voted for Brexit and moved Conservative in a huge way in May's local elections. It remains to be seen what needs to be done to win over that constituency.