Mark Keans, 39, has terminal cancer and is at home in Brisbane, Queensland, while his four children are in Sydney.
Queensland authorities have refused repeated pleas to grant an exemption to tough Covid-19 travel restrictions.
More than A$200,000 has now been raised after the case caused outrage.
Australia has implemented extremely tough travel restrictions to control Covid-19, including on movement between the country's states and territories.
Mr Keans was initially told he needed to choose just one child who would be permitted to see him.
The state government eventually backed down and agreed to allow all of the children to travel to see their father.
But this was only permitted on the grounds that they spend two weeks in hotel quarantine at their own expense. They would also only be able to visit their father in full personal protective equipment (PPE).
"My wife turned around and says so what you're expecting us to pay is more money to visit him then what it's going to cost to bury him," the children's grandfather Bruce Langborne told broadcaster 7NEWS.
A GoFundMe page was then set up with the aim of raising A$30,000, but it soon smashed that target and has hit A$200,000. Prime Minister Scott Morrison donated A$1,000.
Comments on the GoFundMe page have offered support to the family, while many have been offering up harsh criticism to the Queensland state government.
"I donated because we, unlike the Queensland Premier, are compassionate people who do not want to see Mark's children suffer for the rest of their days by being unable to visit their dying father," wrote one, calling the state government's actions "shameful".
Queensland Health has defended its decision.
"We are in the midst of a global pandemic and we need to protect our communities, especially the most vulnerable members," it said in a statement.
"We understand the health directions in place are strict, but they are designed to protect Queenslanders."