I think we can a expect a slight dip in polls because those of liberal leanings (I am a liberal myself) tend to lack confidence in a leader that doesn't know some parts of such a volatile subject such as Syria. Ironically, it is most likely that those who criticize him did not know what Aleppo was as well and are just jumping on the bandwagon to crucify someone. With all of that being said I only tentatively agree with this statement because as an American I have seen many a blunder happen that cause a stir at first but it the end, if it's not too serious and unforgivable, things peter out.
Yes, Johnson's poll numbers will drop because the video clip is trending everywhere on social media. People have been made aware of his ignorance and will thus dismiss his candidacy. He seemed like a good third party alternative for awhile, but it is clear he has no grasp on international politics.
As stated above by another user, any press is good press. I don't think regular democrat voters will honestly care about this instance as they generally don't care about foreign affairs, and regular republican voters will care for the exact opposite reason, but people in the middle I'd argue won't care that much because I'd assume most of them have no idea what Aleppo even was either. Anyway, people will be looking for a third choice this election as both major party candidates have over 50% unfavorable ratings.
Although Gary Johnson looks a little bit silly today, he has handled the gaffe well, and after an initial drop, I expect this will actually increase his numbers as his name gets out there a little bit more. People are looking for an alternative to Clinton and Trump, and Gary Johnson, for the most part, is a sane choice.
Libertarian presidential candidate Gary Johnson has shown himself to be ignorant of major world events; like the tragedy in Aleppo, Syria. However, his ignorance on foreign policy will not likely cause his poll numbers to drop. Firstly, his poll numbers were never that high to begin with. Secondly, his supporters do not have much concern for foreign policy matters either.