Victims and their advocates were invited to Sydney's Kirribilli House to share their stories on Saturday.
The small group thanked Ms Gillard for allowing their voices to be heard.
"Upmost gratification. Gratitude to the Prime Minister," said Pamella Vernon, who attended the event.
Ms Gillard told the survivors that the day was about recognising their work in bringing about the royal commission, which will investigate what happened to them and thousands of others.
She says if it was not for the victims and their families spending decades fighting for justice, the commission would not be happening.
"[Friday's] announcement is a tribute to you for having sustained that campaign after many, many long years," she said.
"I can't promise you there are easy days ahead.
"I suspect there are some very traumatic days ahead as people come and tell what happened to them, many of them for the very first time."
The commission's main focus will be to investigate systemic failures within church and state-run institutions in preventing and dealing with child abuse.
It will have the power to set up a special investigations unit which can provide evidence to police, and will also be able to recommend law changes and consider compensation.
The terms of reference have been , but have attracted some .
Leonie Sheedy from the Care Leavers of Australia Network says many other forms of abuse have been common.
"I think sadly they have neglected the criminal assaults on children, the unpaid labour in the laundries and on the farms and in the orphanages," she said.
"They've neglected the psychological abuse, being told that you're a no-hoper every day of your life."
Bob O'Toole from the Clergy Abused Network says the mere existence of the royal commission will help.
The Clergy Abused Network helps victims in the Hunter - a region that has seen some of the country's worst cases of child sex abuse.
Mr O'Toole says he is largely pleased with the terms of reference and he expects many who have suffered abuse at the hands of clergy feel the same.
"I think the people have felt deterred simply by the fact that it's all too much," he said.
"Those people that I know that felt like that - now that they have done something positive about it - feel much, much better and it's greatly improved their outlook on life and their self-esteem.
"The time frame in which the commissioners are going to have to give reports, I think that's good.
"I hope that it's a great thing for our country. Our particular region has suffered fairly horrendously, so there'd be a lot of people rejoicing."
The six commissioners are expected to hold a telephone hook-up on Monday and their first face-to-face meeting scheduled for Wednesday.
They have been given until the end of 2015 to deliver their final report.
In an interim report due at the 18-month mark, they will be required to say if they need the commission to go beyond three years.