no. any gifts given within 7 years of death go towards the estate for death duty purposes only. the value of the estate at death must be divided according to the will and should not take into account any gifts given prior to death.
your brother, as the executor, has a duty to execute the will as stated. he should contest the will himself if he has a problem with it, it is not for him to decide how much to give you. if he doesn't follow the will exactly as stated, then if i were you i would go and see a solicitor.