Well, I guess it depends on what your definition of a 'gentleman' is!
I think, generally speaking, a gentleman is percieved to use good manners at all times, be educated, debonaire, stylish and charming, always stay calm in the face of adversity, be noble, chivalrous and heroic when the time is right.
I saw a film years ago, I can't remember which one, in which a stricken airliner was at risk of falling out of the sky. Everyone was panicking and making an ass of themselves except for one elderly 'gentleman' who stayed calm and polite ALL the time. The steward(ess) asked him why he maintained his dignity and he replied with something along the lines of, 'Sometimes 'style' is all you have left.
I personally think there's far too much emphasis on things like manners. Don't get me wrong, I do believe there's time and place for them, but to 'use a butter knife when noone else is around' and the like strikes me as a complete waste of time and effort.