Answer

The Acharya publicly associated with / backing the film 1080: The Legacy of Mahaveer was:

Khatargachacharya Shri Jin Piyush Sagar Suri also written as Acharya Jin Piyushsagarsuri.

Why did he back it?

The film is connected with the history of the Khartargachch / Kharatara Gaccha tradition within the Shwetamber Murtipujak Jain sect.

Its story is set around Vikram Samvat 1080 and presents the role of Jain Acharyas such as:

• Acharya Vardhaman Suri
• Acharya Jineshwar Suri
• Buddhisagar

The broad purpose appears to have been to present a historical-religious narrative about the reform of Jain conduct and the strengthening of Jain dharma against lax or improper religious practices associated with Chaityavaas in that period.

Important Note

There was also opposition from sections of the Jain community. Some Jains objected to the film because they felt that portraying sacred Jain figures, monks, or Bhagwan Mahaveer in a commercial film could hurt Jain religious sentiments.

Takeaway

So, the Acharya connected with backing the film was Khatargachacharya Shri Jin Piyush Sagar Suri, likely because the film highlights the legacy and historical importance of the Khartargachch tradition and its Acharyas in preserving Jain discipline and dharma.