Preliminary reports say it passed 100 feet above the first 2 aircrafts lined up on the taxiway, 200 feet above the 3rd aircraft and 400 feet across the last one.
The reason why Gander is talked about a lot more than the other Canadian cities is for a couple of reasons:
1- Their airport is not designed to handle that many airplanes due to its size but also due to the personnel that work there (CBSA, RCMP, ground and tower crew...)
2- All (or at least most) of the trans-Atlantic flights (which are generally bigger airplanes) landed there)
And like you mentioned the population doubled because the town is not designed and made to handle that many people.
Although it's a human that avoided the collision, it is also a human that caused it... Not taking away credit from the controller at all, he did an extraordinary job but software will not make mistakes like the one that the Cirrus pilot did...
