The financial loss from the temporary closure of the site is not yet known.
Graeme Stephens, chief executive of SkyCity Entertainment Group, said there would be a financial impact from the closure and damage from the fire.
"There's clearly a loss ... this is the first time in the company's history that we would have everything shut; it's a really weird time to be on property without a single customer in any restaurant or hotel. There will be an impact from that.
"We're trying to contain the closure to obviously yesterday and today but hopefully tomorrow we will to be able to re-open, hopefully from the afternoon on."
Stephens said it was "impossible" to estimate the economic impact of the fire, damage caused to the International Convention Centre and the delay, at this stage.
Fletcher Building chief executive Ross Taylor acknowledged the impact the fire at its construction site had on SkyCity and the Auckland CBD.
In a statement, Heart of the City said the situation was "very upsetting" and immediate impacts would be felt across many businesses in the Auckland city centre today, and longer-term.
During the update this morning, Stephens called the fire "devastating" for SkyCity and said the damage caused was significant.
SkyCity's Auckland business opened in 1996 and is home to more than 10 restaurants and bars, a 700-seat theatre, convention centre on Federal St and two hotels. About 3500 staff work at the Auckland complex.
The Auckland site made revenue of $568 million in the 2019 year to June 2018. Its EBITDA growth in FY19 was up 2.8 per cent to $267.9m. It is the biggest earner for the company which also operates sites in Hamilton, Adelaide and Queenstown.
Gaming revenue from the Auckland site was up 4.9 per cent in the year while revenue from non-gaming such as accommodation and hospitality was flat.
SkyCity reported a $144.6m net profit after tax in the year to June 2018, down 14.7 per cent. The casino and entertainment operator had an annual turnover of $14 billion in the year - up 19 per cent from the year earlier.