How can a father be convinced to give up pornography channels, and how can one safeguard oneself from watching such material?

To deal with the problem of your father watching forbidden things, seek Allah’s help to lower your gaze from forbidden images. Adhere to congregational prayers in the mosque and associate with righteous people to help you advise your father.

Pray for your father’s guidance, be gentle with him, and engage him in good conversation. Ask righteous people to supplicate for him, and strive to marry to maintain your chastity. Increase in voluntary fasting, dhikr (remembrance of Allah), and reading books of encouragement and deterrence. Always remember that Allah is watching you.

Be good to your father in word and deed, for the call of one's state is more eloquent. His right to dutifulness is great, even if he commands you to commit shirk (associating partners with Allah), and accompany him in this world with kindness. Open beneficial channels to occupy his time away from corrupt channels.