Is a Muslim student obligated to quit his job if all available jobs in a non-Islamic environment involve forbidden things (such as selling pork), given his knowledge that all available jobs include forbidden elements?

It is not permissible to work in a place where pork, alcohol, or other prohibited items are sold, except in cases of extreme necessity, such as someone on the brink of perishing. Permissible jobs are numerous, so you should supplicate and hope in Allah.