Your OP Title is incorrect.
We have 840,000 absentee ballots to count tomorrow.
As it stands from the Interior Ministry:
Hofer 51.9% Van der Bellen 48.1%.
The map, in the below Interior Ministry link shows that Hofer won everywhere, in blue, and that Van der Bellen only won Wien and Vorarlberg which are in yellow.
Österreich - Bundespräsidentenwahl 2016
Hofer has 1,937, 863 votes and Van der Bellen has 1,793,857 votes.
http://www.wahlhochrechnung.at/
Tomorrow the 840,000 absentee ballots will be counted. Which of course is where they'll steal the election from Herr Hofer.
I should add, we wouldn't care about the Presidential Election normally, as it's mainly a Ceremonial role, but the President does have one crucial power, that he can dismiss the Government and call a new General Election.
This is the only reason we're caring about this, Herr Hofer will call a new General Election, Alexander Van der Bellen won't.
If we go on the votes and the percentage from the First Round, the FPÖ would have formed a new Government now, were it the General Election.
The FPÖ is now unstoppable, everyone knows this....they might steal this for Van der Bellen on the absentee ballots, because in the Presidential Election you need 51% plus 1 to avoid a Round Two of voting.
The General Election you just need the most votes and the bigger percentage....so in the General Election if you get 36% you win, although you will have to form a Coalition.
The opinion polls for some time have had the FPÖ at 40%, in the General Election this is more than enough to form a Government on it's own, judging from Herr Hofer's votes tonight the FPÖ is now well beyond that 40% and this would be a landslide General Election victory.
It's going to happen, it's now unstoppable.
Edited to add more comment.