The Royal Commission into Institutional Responses to Child Sexual Abuse is currently focused on the Victorian state town of Ballarat and how the church dealt with complaints against priests, many dating back to the 1970s.

It is allowing Pell, who was once based in Ballarat, to give evidence about what he knew via video-link from Rome because he has a heart condition.

A group of victims and supporters will be there as witnesses, after a crowd-funding campaign was overwhelmed by support and raised almost four times its target in less than a week.

David Ridsdale, who was abused by his uncle, paedophile priest Gerald Ridsdale, said it was not a “witch hunt of Cardinal Pell”.

“It's a truth hunt,” he told the Australian Broadcasting Corporation.

“What we're hoping for is the same we've given, which is just truth.”

David Ridsdale has told the inquiry that he phoned Pell in 1993 to complain about his uncle abusing him and claims Pell tried to buy his silence, an allegation the cardinal has strongly denied.

Pell has always denied knowing of any child abuse occurring in Ballarat, including by Gerald Ridsdale who preyed on dozens of children over two decades.

The cardinal's evidence is keenly anticipated after former Ballarat Bishop Ronald Mulkearns told the inquiry on Thursday he had not known how to handle allegations of child sex abuse.

“I certainly regret that I didn't do things differently,” the 85-year-old said.

“Those days, it was a long time ago – we didn't know quite how to deal with these things.”

Anthony Foster, who has two daughters that were abused by a paedophile priest, said he wanted clarity from Pell on what went on.

“We want to hear the truth. He's worked his way right through the hierarchy, right up to the top of the Catholic Church,” he said of Pell.

“So we really want to hear the truth about what happened.”

Australia ordered the Royal Commission in 2012 after a decade of growing pressure to investigate allegations of paedophilia across the country.

It has so far heard claims of child abuse involving churches, orphanages, community, sports and youth groups and schools.