Complex sentence: Korsakov immediately recognized Gretchaninov's extraordinary musical imagination and talent, giving him much extra time as well as considerable financial help, which allowed the young man, whose parents were not supporting him, to survive.
Split into simpler sentences: Korsakov immediately recognized Gretchaninov's extraordinary musical imagination and talent and gave him much extra time as well as considerable financial help. This allowed the young man, whose parents were not supporting him, to survive.