Is it obligatory to make up for the days in Ramadan during which one watched pornography, what is the ruling on watching such materials and masturbating while fasting, and how can one get rid of addiction to these materials?

You must return to righteousness and repent from unleashing the gaze, for it corrupts the heart, while being mindful of Allah's watchful eye and contemplating death.

Deliberate masturbation during the daytime in Ramadan is among the things that invalidate the fast. As for semen discharge due to repeated looking, it invalidates the fast, and it is more cautious to make up for those days. If what is discharged is madhy (pre-seminal fluid), its ruling is different.