The seeding rate calculator at canolacalculator.ca defaults to 60% seed survival, which is fairly typical for canola in Western Canada.
If choosing the default isn’t your style, the best way to find out the typical seed mortality in your system is to start doing your own stand counts and cross-referencing that with your actual seeding rate in seeds per square foot.
The following can also help to figure out what influences survival…
You might be at 70% or more if: Seed goes into warm, moist soil in mid May. The drill’s ground speed is slow enough to improve consistency of depth for each row. You use a low rate of seed-placed fertilizer.
You might be at 50% or less if: Canola goes into cool soils. This reduces survival but also greatly expands the germination period and reduces stand uniformity. Seed goes into dry soil. In dry conditions, seeding deeper to reach moisture might be a good strategy to at least get some seeds germinating, but this will keep survival low. High rates of seed-placed fertilizer will also reduce survival, especially in dry soils.
This article has more detail on how to improve seed survival.