لَعَلَّ conveys possibility or hope. لَعَلَّكَ thus means “perhaps you.” Together with تُرْزَقُ بِهِ, the statement means “perhaps you receive provision because of him.”
تُرْزَقُ is a present passive verb: it speaks of receiving provision. The pronoun in بِهِ refers to the other brother.
This is not a fixed economic formula guaranteeing a particular income to every supporter. The Prophet ﷺ reminds the worker not to reduce his brother’s learning and devotion to an immediate financial calculation.