Last month, FIFA secretary-general Jerome Valcke warned the stadium could be excluded from football's showpiece event later this year due to severe construction delays, reported Xinhua.
An inspection by FIFA officials Feb 18 will determine whether the venue will remain on the tournament schedule.
According to local daily Folha de S.Paulo, the number of workers at the stadium has increased from by 150 to 1,114 since FIFA's last inspection Jan 21.
Grass has also been laid and 15,000 seats installed while the roof is almost complete.
But Curitiba's urban planning secretary Reginaldo Cordeiro said Thursday that FIFA's stadium consultant Charles Botta had requested more workers to speed up works.
"The amber light is still on and it's only going to be turned off when we finish," Cordeiro was quoted saying.
The stadium's owner, Atletico Paranaense football club, is seeking a loan of $27 million from Brazil's national development bank BNDES to accelerate the final phase of construction.
The 43,000-seat venue in Brazil's south is due to host four World Cup matches.
It is one of five stadiums yet to be completed for the June 12 - July 13 tournament, despite a December 2013 deadline imposed by FIFA.