My Galaxy Tab 10.1 fell straight from the bed. Will this influence the Tab life? Last night, I left the Tab next to me and it fell from my bed onto the floor. The Tab now has a crack in the upper right corner and a little depression between the frame and the screen.  Will this affect the Tab's lifespan/usability or is just cosmetic?
Anytime you have a crack or gap in a device where it isn't supposed to be can mean you may run into additional issues. The device will now be more prone to issues from moisture and/or dirt and it may not be as sturdy and could be more likely to break even more when moved the wrong way or dropped (even from a lower height).

If there are cracks in the digitizer (the glass that you touch), it can cause issues with recognizing input from your fingers. And you have the possibility of glass splinters ending up in your finger (depending on how the glass cracked). To help with the possibility of splinters or having it crack further, a screen protector could help (but it isn't guaranteed to prevent anything else).

But the act itself of being cracked (as long as it didn't cause internal hardware damage or too much damage to the screen), shouldn't cause any shortening of life of your product. It is just what may happen after the crack (moisture, dirt, etc) that can shorten the life of the tablet.