The specific claim that "Eskimos have X words for snow" is heavily disputed.
However, is the general concept that certain cultures' languages often have a large number of words for things that are important in that culture valid?
Examples of this I recently encountered include Lonely Planet's guidebook on Mongolia saying that Mongolian has a large number of words for horse skin colour compared to English (IIRC), and a claim on the BBC that Japanese has a larger vocabulary for apologizing than English (The many ways to say sorry in Japanese)