The polls are if anything getting closer, rather than the opposite. So any prediction the Tories will get more seats than in their 1983 landslide (when they were c16% ahead nationally) looks.....brave.
Depends a lot on youth turnout and how much of the Liberal Democrat vote holds up. A decline in Liberal Democrats seems to result in 2/3 going Labour and 1/3 Tory so if LibDems stay above 15% bad news for Labour, but if under 12% helps them. A lot of polls are going on younger voter turnout around 55% so if younger voters like 2015 don't show up, I think Labour likely will get less than 200 seats and Tories over 380. If however younger voters show up in similar numbers to 2017 which based on registration seems quite possible, than probably a Tory lead of 6-8 points if things don't change, but could get even closer. In this case, Tories right on the line for majority although I think applying a uniform swing is risky. With Brexit being main issue, I think a lot of Labour seats that went over 60% leave will see much bigger swing towards the Tories and you could even see some seats Labour won by 20 points flip. On other hand those with younger demographics and over 60% remain, I could easily see Labour holding onto many marginals that on paper may look vulnerable.
Also there is the tactical voting question too. Are Liberal Democrats around 13-14% nationwide or is this heavily concentrated in London and other areas of South where many Labour voters will tactically vote Liberal Democrat while in much of the rest of the country are struggling to hit 5%. If nationwide, good news for Tories, if more concentrated could make race closer than expected.