Trump could possibly do so something to make up the differnce. It is a large differnce, but there are stll a little over two months before the election and just about anything is possible. It is not likely that he will close the gap and come out ahead, but it is still possible.
In theory, Trump could probably pivot to some reasonable positions and pull a 180 on his rhetoric. However, this would immediately lose him a significant amount of support that he's already gotten, and he's certainly not going to do anything that damages his brand with his hardcore supporters. When this is all said and done, Trump is going to cash in on this run like nobody else, and to do that he needs his rabid fans that don't listen to "The Lamestream Media."
Over the past couple of weeks, there have been a number of very negative revelations about Donald Trump and his campaign staff regarding questionable business practices, and this has hurt his credibility in the polls. At this point, he will not be able to spin these truths into something positive and somehow raise himself up out of the muck that he finds himself in.
Donald Trump has two chances of winning the election: slim and none. There is nothing, at this point, that Trump can do to catch Clinton in the polls by election day. Trump has self-destructed his own campaign; much of it from the very beginning of his campaign's launch. Trump has offended too many and alienated too much of the Republican Party. He has also energized Democrats to come out and vote against him.