No. Jainism is not a branch of Hinduism.

In simple words:

• Jain Dharma is an independent, very ancient religion of India.
• It is based on teachings of the Tirthankars (like Bhagwan Rishabhdev, Mahavir Swami), not on the Vedas.
• Jain scriptures, vows, paths of liberation, and philosophy are separate from Hindu traditions.
• Because both developed in India, there are some cultural similarities (language, festivals style, dress, etc.), so people sometimes think Jainism came out of Hinduism – but that is not correct.
• Jain texts themselves present Jain Dharma as anādi (beginningless) and independent, not as a sub-part of any other religion.

So: Jainism and Hinduism are two different religious traditions, even though they have coexisted in the same land for thousands of years.