The basic principle is that every Muslim is required to seek a halal job so as to earn his living in a lawful way, and to steer clear of doubtful matters and that which is haram.
A Muslim who works in a store where pork and lottery tickets are sold should quit that place and search for a lawful job. In case he has no means but to remain in that place for a while until he finds a lawful job because he is financially straitened, then he is permitted to do so. However, he should quit the place the moment he gets another opportunity, even if he must take a cut in pay.
Dr. Muzammil Siddiqi, former president of the Islamic Society of North America (ISNA) and member of the Fiqh Council of North America, states:
“For a Muslim, it is forbidden or haram to sell things that are forbidden. Every muslim should try to find a halal job as soon as possible. Be active in seeking another job even if it pays a little less than what you earn now.
If you cannot afford to live and maintain yourself and your family without a job, then work at this job until you find another one. Quit this job as soon as you find a halal position. May Allah help you.”