It is well known that the principle “Your life takes precedence over the life of your fellow” (Bava Metzia 62a) applies to all matters, as does the principle of “Your own poor come first” (ibid. 71a). The same does apply to Torah study — one’s own learning takes precedence over others. But if he cannot learn for himself then he should do his utmost to have his children learn Torah and that they make learning their occupation. Similarly if several siblings have a brother who is a talmid chacham, they should support him so that he can devote himself to Torah study without worry or distraction. Aside from the reward they will gain from their efforts, they will also be blessed by their father and mother — there is no greater form of honoring one’s parents than this. Any Torah scholar from one’s immediate family takes precedence over scholars from outside the family and the family member should be the one to support.
One who does not have the means to support a Torah scholar financially should support him physically by attending to his needs, such as doing errands for him or the like. But one is only obligated to do what one is capable of doing.