Disciples of Jesus can be considered an occupation if the role is entered into for profit or as a person in an employed position at a non-profit entity. Since this is a religious role it is generally not expected that a disciple would make a lot of money for themselves.
Being disciple of Jesus is like following a certain religion or values. It can't be an occupation since its a way of life and one follows those values because they believe in it, not because they get paid for it. People who really are interested in following those values will not need convicing.
I do not believe that being a disciple of Jesus should be considered an occupation. Preachers, pastors and the like devote their lives to teaching faith and spreading the word of the Lord. While those who devote their lives to following Jesus and spreading his word have a strong conviction and passion for what they do, I do not believe it should be considered as an actual career.
The idea of an occupation mostly has to do with what someone does for a living. Traditionally deciples of Jesus do not make any money from this, so it would not make sense to consider it an occupation. However, if an organization has a job called " deciples of Jesus" they might be considered missionaries.