Does Google Chrome have a significant impact on MacBook battery life compared to other browsers?
Battery Life is different than Battery Duration. Battery life will be tied to the maintenance and usage you give to a battery. To put it simply, if your battery is designed to be charged 100 times before it dies (cycles), then using the 100 charges in one month will be the same as using them in 1 year. (or almost the same, since there will be a small loss of power when the battery is idle).

What I mean is, the battery life shouldn't be greatly affected by any application's usage pattern. But…

The truth is that battery duration is definitely affected by the power consumption. In other words: the more the power your computer uses, the less the batter will last with charge, before it requires to be recharged. 

With that logic in mind, Chrome is a moderately CPU intensive application on its own (a tradeoff that is inherited by its One Process Per Tab design). It taxes your hardware a little bit more when creating new tabs and it uses slightly more RAM in order to keep things smooth. In exchange, you have a very solid -hard to crash- browser that will be able to keep working even if some of its tabs are literally dead. 

Despite that, however, Chrome has Flash (as an extension you can disable). It uses the "same" Flash, but bundled internally. If chrome uses some more battery (something that I have yet to see in real life), Flash uses probably all the battery you can throw at it, but not because Flash needs battery, it's because it needs CPU power, a lot, all the time. CPU power needs electricity. Batteries have Electricity. In the absence of a power outlet, guess who's there to provide juicy power to that hungry CPU? Yes, mamma battery. 

So Flash will definitely decrease your battery charge duration (and in turn, it will force you to cycle charge your battery more often, therefore decreasing its life), but this will also happen on Safari, Camino, Firefox and possibly other applications or browsers that use Flash.