There is no doubt that Riba is amongst the most abhorrent of systems and action in the Sight of Allah. Earning from it and engaging in it is simply unacceptable for a Muslim. As such anyone working in a bank really should make every effort to find a different job. This does not mean the person should put themselves in great danger and suffering, but in practical terms looking for another job which does not buy and sell Riba is not that difficult, insha Allah.
May Allah make such decisions made by Muslims one where there is ease and facilitation by His Mercy.