Datafolha interviewed 3,758 people across Brazil on June 6-7 and said the poll had a margin error of 2 percentage points.
During his flight to Brazil, Francis also expressed concern about the elderly, saying older people should not be isolated or "thrown away ... as if they had nothing to offer us."
"A people has a future if it goes forward with bridges: with the young people having the strength to bring it forward and the elderly because they have the wisdom of life," the pope said. The elderly have "the wisdom of history, the wisdom of a nation, the wisdom of a family, and we need this."
Francis has spoken often of the need for humility in the church, and he kept to that message Monday; the pope carried his own black hand luggage as he boarded a special Alitalia flight from Rome.
"Every pope is different, and Pope Francis is showing himself to be extremely charismatic, with a language that is simple and direct," Sao Paulo Cardinal Odilo Scherer said.
Playing out alongside the papal visit is political unrest in Brazil, where widespread anti-government protests that began last month have continued and are expected to occur outside Rio's Guanabara Palace, the seat of state power where Francis is to meet with President Dilma Rousseff on Monday evening.
With the exception of gay rights groups and others angered by the church's doctrine against abortion and same-sex marriages, the target of most protesters won't be Francis but the government and political corruption. The pontiff is said to support Brazilians peacefully taking to the streets, and when he was a cardinal in Buenos Aires he didn't shy from conflict with Argentina's leaders as he railed against corruption.
When Francis talks with Rousseff, they are likely to focus on the poor. Upon taking office, the Brazilian leader declared that eradicating extreme poverty was her top goal as president, and she has expanded a network of social welfare programs that have helped lift almost 30 million Brazilians out of poverty in the last decade.
"Unlike his predecessors, who had a theoretical understanding, Francis has a pastoral understanding honed by living and working in working-class neighborhoods of Buenos Aires," said Joseph Palacios, a sociologist at Georgetown University and former Catholic priest who has studied the church.
That's evident to Maria Nascimento, a 60-year-old Catholic living in the Varginha slum that Francis will visit this week.
"God chose wisely when he decided to send this humble man to lead the church," she said, standing in her kitchen where photos of grandchildren's baptisms were stuck to her refrigerator with magnets.
"There's going to be a huge impact on Brazil after he has come and left, after his feet have walked these streets in our slum. He's going to help the church in Brazil, the love here for him is growing so fast."
Associated Press reporter Bradley Brooks reported from Rio de Janeiro. Jenny Barchfield contributed to this report.