If this is his primary job and he cannot decline it, then there is no issue for him, and he can perform his job without participating in the drinking activities.
However, if he can decline without harming his work, that is preferable, based on Allāh’s saying: “And when you see those who engage in [offensive] discourse concerning Our verses, then turn away from them.” [Al-᾽An῾ām: 68], and His saying: “So do not sit after the reminder with the wrongdoing people.” [Al-᾽An῾ām: 68].
The matter is to be evaluated based on each situation accordingly, and there is no single ruling that applies to everyone. The circumstances of the worker and those at the event should be considered. The ruling is easier if they are not Muslims and not bound by our Sharī῾ah, compared to if they are Muslims.
Fatwa issued by Dr. Khālid Naṣr