Hi Boslandew:
The Victoria-Vancouver route is a bit unique because the smaller island city (Victoria) is the provincial capital, and the much larger mainland city (Vancouver) is the business center of the province - arguably the business center of Western Canada.
The downtown harbour in Victoria that the floatplanes and helicopter operate from is within walking distance of the provincial legislative building and many government offices. I am going to guess - and this is an uneducated guess - that perhaps as much as 80% of the traffic on the helicopters and Twin Otters is government and business traffic, with a very large proportion of the Twin Otter traffic being 'out and back the same day'.
The two communities are also served by hourly Dash 8 service. The Dash 8s operate from the Victoria airport, which is quite a long way out of town (very close to the ferry terminal, in fact). The Dash 8s probably pick up 98% of the connecting airline passengers, with the helicopter (which does the downtown Victoria to Vancouver airport) route picking up perhaps the other 2% - that being the first-class traffic.
To give you a rough idea of scale, the greater Victoria area has a population of about 300,000; and the greater Vancouver area has a population of about 3 million.
Michael