Watching pornographic material is forbidden.
It is against the commands of Allah.
Allah the Almighty commands:
“Tell the believing men to reduce some of their looks and guard their private parts, because that is purer for them. Verily, Allah is All-Aware of what they are trying to do.” (24:30)
“The believers will attain what they hope for. They are humble in their prayers. They work for improving (themselves and others). They cover their private parts. Except to their spouses and to those in their guardianship. They cannot be blamed for it. Whoever goes beyond this, they are the transgressors.”(23:1-7)
As you see, “avoiding whatever is vain and frivolous” is counted as one of the qualities of believers. So in order to be counted as a “believer” in the sight of Allah, one should avoid pornography.