Does hand gesture have an impact on meditation or attainment of Nirvana?

The question regarding the gesture while sitting for meditation has always intrigued me. When I tried to ask this to a Vipassana teacher in my 10-day course, he put it off saying I should concentrate on meditation first without worrying about these matters. Does it mean that it doesn't make any difference? I personally use the dhyana mudra (fore-finger touching the thumb in a circle, and other three fingers straight out) while sitting cross-legged. But in many of Buddha's statues, I've seen him keep the left hand over right, and in some others, thumb touching forefinger and hand kept straight across the chest gestures. Want to know from advanced practitioners, what do the Buddha's postures indicate? More importantly, does having a certain gestures have any good or bad effect on our vipassana practice?