If someone keeps missing Jumu'ah due to his job wouldnt this be sinful since it's obligatory for men to attend Jumu'ah? Are there any permissabilities that one may have to miss jumu'ah due to his job?

Jumu’ah prayer is obligatory on every Muslim, and is not permissible to miss it for any reason except in case of necessity, like sickness. The Prophet Muhammad (SAW) said, “The Friday prayer in a congregation is an obligatory duty upon every Muslim, with the exception of four: a slave, a woman, a boy and an invalid (sick)”. He also said: “people must cease to neglect the Friday prayers, or else Allah will seal their hearts and then they will be among the unwary.”

In your case, you need to know the reason for not attending the Friday prayer; if it is because of laziness, then it is forbidden to miss it. If it is because of your job, then ask the one who is in charge to make your lunch time in the same time of the prayer, that way you will not miss it, or try to take off during the prayer, and make up the time you missed, or otherwise find another job.