It's not that simple. It could, for example, produce a full 8 bits of depth of a certain color like blue, but the entire range doesn't have to match what you see on screen. I think gamut (the total width from lightest to darkest tone) is a different concept from bit depth. You could have an 8 bit (for all colors combined) image with the same gamut, but instead of a smooth graduation from light to dark you'd see blocks of solid color.
Just like you can calibrate your monitor, there are ways to calibrate printers. They're not cheap, in general, there's a Spyder for printer calibrating but it costs more than the 2 Pro. However the Spyder Suite pack should have come with their cheap printer profiling software, which doesn't actually use a sensor at all, it uses predefined profiles for selected printers that you can then fine tune by printing test sheets and adjusting to taste. I've recently switched to a color laser which they don't really have any specific profile for so it's largely worthless for me (I have the Spyder 2 Suite as well), but.. it might be useful for you.
In any case I do my serious photo printing at Costco, using their.. well.. I don't know what kind of printer they have, it seems to involve lasers in some fashion, but it's a printer made for printing photos. I think it uses an entirely different process that I'm not familiar with. There's a fairly well known way to get profiles for those printers. There's a website,
www.drycreekphoto.com, that has profiles for places like the Costco that I use. Not for their particular model of printer, but profiles made for their individual printer machine, because each unit will apparently differ from the others. Like monitor profiling the profiles are updated on a regular basis, they have a profile dated from May 10th for my store.
You use the profile as the last step of working with the image, using the proof colors option. Tim seems to be suggesting that Photoshop has a pre-made profile for the printer already, which should be better than nothing. Drycreek has a brief intro on how you go about using the proofing function.
I'm no expert at it, but I've been reasonably pleased at how my prints have matched my screen. I haven't tried printing without using the profile at Costco though, so I can't really say if the profile has anything to do with it.
It's also possible that Canon may offer profiles for their printers on their web site. I've been searching far and wide for a standard profile for my printer (yeah, I know I said that each printer unit can differ, but there seems to be at least some value in a standardized profile for an entire model line), but although HP provides profiles for some of their higher end color lasers, they don't offer a thing for mine (although it has a native color mode option that's just screaming for a decent profile).
