The 27-year-old striker died on Monday, a day after playing his first match for his new club. His body was due to be flown back to Ecuador just after midnight on Thursday but the flight has been delayed until noon local time (0900 GMT).
"The official medical reports were issued by official state entities and stated that the sudden death was caused by heart failure," the club said in a statement. The club added that his body will be repatriated on a private plane.
On Tuesday, Ecuador football federation president Luis Chiriboga said the 27-year-old Benitez had been taken to the hospital with sharp stomach pains, developed peritonitis and died of cardiorespiratory arrest.
Relatives of Benitez including his wife, Liseth Chala, and several players and team officials gathered Wednesday at the Doha airport to await the arrival of his casket. But soon after an ambulance with the casket pulled up, the family was told the flight didn't have all the necessary approvals and would go in the morning.
As they waited, the team presented Chala with a signed jersey from all the players and bearing the nickname Chucho on the back.
"He was a good man and I lived a good life with him," Chala said. "He was very happy to play football in Doha and he was grateful for this chance. We thank the club for this solidarity in this difficult moment."
A funeral was planned for Thursday in the Ecuadorian capital, Quito, along with separate tributes to the player.
Anibal Fuentes, head of the provincial sports authority for Quito, told Radio Sonorama that "the coffin will make a stop at the Casa de la Seleccion (the national team training centre) for a small ceremony, and will then be transported to the General Ruminahui coliseum" sports arena, which has been set up to receive the family and thousands of fans.
Benitez was a powerful striker who helped former club America to win the Mexican championship last season. The father of three, who also played for Birmingham, scored 24 goals in 58 appearances for Ecuador and was in the country's World Cup team in 2006.