  We present a new sample of 158 galaxies at redshift $z>7.5$ selected from
deep \jwst\ NIRCam imaging of five widely-separated sightlines in the CANUCS
survey. Two-thirds of the pointings and 80\% of the galaxies are covered by 12
to 14 NIRCam filters, including seven to nine medium bands, providing accurate
photometric redshifts and robustness against low redshift interlopers. A sample
of 28 galaxies at $z>7.5$ with spectroscopic redshifts shows a low systematic
offset and scatter in the difference between photometric and spectroscopic
redshifts. We derive the galaxy UV luminosity function at redshifts 8 to 12,
finding a slightly higher normalization than previously seen with \hst\ at
redshifts 8 to 10. We observe a steeper decline in the galaxy space density
from $z=8$ to $12$ than found by most \jwst\ Cycle 1 studies. In particular, we
find only eight galaxies at $z>10$ and none at $z>12.5$, with no $z>10$
galaxies brighter than F277W AB=28 or $M_{\rm UV}=-20$ in our unmasked,
delensed survey area of 53.4 square arcminutes. We attribute the lack of bright
$z>10$ galaxies in CANUCS compared to GLASS and CEERS to intrinsic variance in
the galaxy density along different sightlines. The evolution in the CANUCS
luminosity function between $z=8$ and $12$ is comparable to that predicted by
simulations that assume a standard star formation efficiency, without invoking
any special adjustments.
