The county fire service said power had also been restored to 111 of the 116 affected properties.
A helicopter on site will remain in use into Friday, with each drop unloading 1,000 litres of seawater onto the blaze.
A spokesperson for the Sizewell B nuclear power station, about three miles (5km) from the fire, said it was monitoring the “dynamic situation”.
Homes and a holiday caravan park were evacuated after the fire broke out and there are fears for rare birds and wildlife whose home is the heath and nearby RSPB Minsmere.
The “large-scale, wind-driven” fire was declared a major incident on Thursday morning, due to the size and complexity of the blaze which was helped by south-westerly winds.
On Thursday evening, Suffolk’s chief fire officer, Jon Lacey, said difficult terrain and limited access routes were making it hard for crews to reach some areas of the wildfire.
He confirmed that approximately 100 to 150 people had been evacuated from their accommodation.
An update on the fire service’s website said it was being supported by firefighters from neighbouring brigades, with engines also being sent from London.
“We have also requested additional national support, including wildfire specialist appliances, officers, and tactical advisers,” it said.
“Around 50 people have received support through the rest centre, which remains open.
“We expect the response to continue for at least the next 48 hours.”
Prime Minister Andy Burnham pledged to give the fire service “all the support it needs” to tackle the “very serious” heathland blaze.
Communities Secretary Angela Rayner praised firefighters for their “skill and dedication and bravery”.
Green Party leader Zack Polanski has called for Burnham to host an emergency Cobra meeting to discuss the outbreak of wildfires in Britain, including in Suffolk.
