Short answer: Yes. In Jain Dharma, watching pornography is paap (sinful) because it inflames passions (rāga), causes influx of karma (āsrava), and violates the vow of brahmacharya (chastity).

How Jain principles view it

• For monks and nuns (mahāvrata): Any sexual thought, sight, or act breaks brahmacharya.
• For laypeople (anuvrata): It is an atichāra (transgression) of the brahmacharya-anuvrata; specifically “viewing obscene material.” It also falls under the anarthadanda-vrata (avoiding purposeless sins) like reading/listening to improper content.
• Spiritually: Such viewing excites the senses, strengthens attachment and passion, and binds harmful karma to the soul.

Traditions

• Both Digambar and Shwetambar traditions uphold brahmacharya in the same spirit; watching obscene content is treated as a transgression. There is no accepted tradition that permits it.

What to do if one has this habit

• Do pratikraman and prāyaścitta with sincerity.
• Practice samayik to calm the mind and weaken passions.
• Set strict limits (saṃyama) on media and devices; avoid triggers and company that encourage such viewing.
• Cultivate anuprekṣā (reflections) on the harms of sensual indulgence and the peace of self-restraint.
• Strengthen bhoga–upabhoga limits and aparigraha to reduce indulgence.

For simple study on these vows and transgressions, see:

• Atichāra of brahmacharya (includes “viewing obscene material”)
• Twelve vows of the layperson (includes anarthadanda-vrata)
• Basic principles and the five vows (including brahmacharya)