Should I keep silent or inform the company about my colleague who is paying bribes to obtain orders for the company's products, knowing that this violates company policy and could lead to his dismissal?

Your duty is to advise the employee to desist from his transgressions and to remind him that Muslims are bound by their conditions and that the Prophet, peace and blessings be upon him, cursed both the briber and the bribed. If he does not desist, you can threaten to report him. If that does not work and he persists in his forbidden actions, then report him to the company official if what he is doing harms the company. However, if there is no harm to the company, and reporting transgressors is not part of your duties, then do not report him to the official, but continue to advise and admonish your colleague and do not show him approval for what he is doing.