The NBC/WSJ poll has been updated to account for the debate. Pre-debate, it had an eye-popping 11-point Clinton lead in the four-way and 14 points the two-way. That lead has settled down a bit:

In a four-way matchup, Clinton now has the support of 46 percent of likely voters, while Trump has 37 percent, Libertarian Party candidate Gary Johnson has eight percent and Green Party candidate Jill Stein has two percent.

And there are signs that it could come down further, as Trump does indeed appear to have rallied his base:

Among only those respondents contacted after the debate, Clinton’s lead shrank to a seven point advantage in both a four-way matchup and in a head-to-head race — reflecting the same margin that Clinton showed in a mid-September NBC/WSJ poll.
After Sunday’s debate, Republicans also showed more support for Trump as their standard-bearer. Before the debate, 67 percent of Republicans said that GOP House and Senate candidates should back Trump, a share that has now increased to nearly three-quarters – 74 percent, including 83 percent of Republicans reached post-debate on Monday.

Although his Trump’s image is still unbelievably bad:

While his standing in the polls improved slightly after his performance Sunday night, Trump’s favorability did not.
His favorability rating now stands at 30 percent positive, 63 percent negative. That’s compared to 29 percent positive and 63 percent negative before the debate.