"More importantly, viewers have been telling us all day that they are impressed."
Mr Gillespie said he "absolutely" expected the audience to grow. "Seven Sharp continues to be second only to Shortland Street on TV2."
The long-running soap attracted just over 500,000 viewers.
Mark Jennings, director of news and current affairs at TV3, said Campbell Live had one of its best starts ever and also believed the audience would grow as the year went on. "We are still essentially in the middle of summer, and people traditionally watch less news and current affairs at this time of year".
The lead story on Monday night was a live interview with Grammy winner Joel Little, the co-writer and producer of worldwide hit Royals by Lorde. Mr Jennings said that interview was key, as was the leaders of both major political parties appearing. "I'm very proud that all our programmes had solid journalism at the heart of their stories.
"All our teams worked hard over the summer to kick off their programmes with top content, and we've started the year in the way we mean to continue - good, strong stories presented in a lively and entertaining way."
Meanwhile, The Paul Henry Show began with 165,000 viewers later the same night. TV3 said that was a much higher audience than the 2013 average for the show it replaced, Nightline, which was 108,200.
Mr Jennings said New Zealand broadcasting had missed Henry.
"It's something very special to be able to launch a new current affairs programme, and I'm very happy with day one of The Paul Henry Show, and looking forward to seeing it develop over the coming weeks."
Seven Sharp, TV One
1. MPs skip Parliament - live interview with Mike Hosking
2. Follow-up story on Kiwis not having access to Australian welfare
3. Reporter Matt Chisholm's brother Nick, who suffered a stroke playing rugby, gets married. He has featured on the show before.
Campbell Live, TV3
1. SkyCity's host responsibility under the microscope.
2. Immigration scam follow-up
3. MPs' attendance at Parliament
4. Summer weather