Oliver told MPs at the Commons health committee that Prime Minister David Cameron was reviewing all the evidence, adding there was a need to "make sure he's brave".
He said his main role in front of the committee was "as a dad".
The TV star has been campaigning for a levy of sugary drinks, amassing almost 150,000 signatures of a petition demanding a Commons debate
During the session, Oliver handed out sugary drinks he had doctored to make sugar levels much more clear.
He said he had worked out how many teaspoons of sugar were in each of the drinks, which included 14 in a bottle of Pepsi and 13 in a bottle of Ribena.
Of the need for a "sugar tax" and the Government's view, he said: "The discussions that I've had have not implied that that is written off.
"The discussions I've had are robust...Mr Cameron is reviewing everything.
"I think where he is positioned for the next five years...we need to make sure that he's brave."
He added that public polls on the need for a "sugar tax are favouring it quite strongly".
Sugar-sweetened drinks are the biggest source of sugar in children's diets, he said.
He said there was a need to be "big and bold" adding: "Who is it that's running the country?
"Is it businesses who are profiting from ill health in our children, or is it us?"
Oliver said he had suggested that a three-year sugar tax should be introduced to see how it worked.
"My suggestion to the Government is that we should implement a three-year sugary drink tax of 20% per litre, which is seven pence on a regular can of soda, and that we should absolutely interrogate it and put a sunset clause on it."
He said the tax would then be removed if it had not been shown it was "symbolic" and resulted in a drop-off in sales.
Earlier, Oliver accused successive Governments of failing children.
He told the committee: "The Government over the last 30 years has done an incredible disservice to children with regards to creating an environment where making a better choice is easy or easier."
Last week, Oliver added his voice to criticism of Health Secretary Jeremy Hunt over his refusal to release a Public Health England review of evidence before the publication of a Government strategy on the issue.
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