Besides Jonas and Gabriel, who has pale eyes?
Jonas and The Giver both have pale eyes. So do Gabriel and a young Six girl named Katherine as others have mentioned. Rosemary also had pale eyes. It is likely that they all are related, and they all have special abilities.
It can be reasonably inferred that the pale eyes are a genetic trait. Jonas does not like his pale eyes because they make him different, and people in the community are trained to reject and fear differences. However there seems to also be a link between pale eyes and the capacity to See Beyond, or the special power to see colors and receive memories.