A "G" doesn't necessarily refer to a gangster. In Queens, among the individuals I'm acquainted with, a "G" is basically a person who has their "shit together"....or someone who is good at life, all around. An individual who is good looking, in good shape, is intelligent, has money, is good with people, is with hot women, is well dressed etc. is a "G." Therefore, the majority of the hip-hop/gangster community are not G's at all due to their lack of brains, money, social skill, class, style etc.
Lil' Wayne is not a G (due to him not being successful in all facets of life, eg. inability to conduct himself appropriately, lack of intelligence etc.).
Jay-Z is a G (high quality lyricism, money, Beyonce, style, class etc.).