@anonymous234 For once the polls were right... Maybe after a few failures they updated their polling strategies well enough? (in the 80's/90's, French pollsters regularly under-polled the National Front and it was a recurrent post-election debate... they manage to get more accurate numbers since about 10 years or so...)
In any case, the second round is done and dusted. For one thing, the polls show (and have always shown) such a margin that even if they were wrong (which, given they were right for the first round, seems unlikely), they would have to be absolutely, totally wrong (it's about 65/35, so a 30 points lead!). Also, despite all the efforts from her leader, the National Front still is seen (rightly, in my opinion) as a racist and anti-semitic party with fascist tendencies (see her latest quip about a WW2 round-up of jews by French police not being the fault of France...). That makes her totally unpalatable for many voters, no matter how much they dislike her opponent. And finally, as I said in an earlier post, the whole FN's strategy since 30 years has been to show themselves as a party-not-like-the-others and that doesn't compromise with mainstream parties. As a result, she has herself cut (or prevented building) all bridges that could bring her more voters.
So, yes she will attract some of the right's (Fillon) voters (about 1/3 apparently), and Macron will struggle to attract all of the left's voters (no more than 2/3 apparently), but that will still leave him very comfortably ahead of her.
She probably doesn't mind that much. Whenever they got to power (in various local elections), the FN proved that they are no better than the others, that they don't have a consistent political line and that essentially they are just good to complain but not to do. So staying in the role of the poor outsider against whom everyone is leagued is a role that she knows very well, and will happily keep playing for the next 5 years... Whether people will keep following her is another question, but at this point I don't see any major change in that regard.