"We have absolutely put him on the witness list," Prosecutor Greg Andres said as quoted by CNBC. "We have every intention to call him as a witness."
Manafort has entered the third day of trial in Virginia on Thursday on charges of bank and tax fraud. Prosecutors will focus on the Trump campaign manager's luxurious lifestyle as a result of the money he earned in Ukraine while avoiding to pay taxes.
Gates remains one of the key witnesses in Manafort's case. He pleaded guilty to charges of conspiracy and lying to the FBI and agreed to cooperate with investigators.
In October, US Special Counsel Robert Mueller indicted Manafort on banking and tax-fraud and money laundering charges related to the work he did in Ukraine from 2006 to 2014. Manafort has also been charged for acting as an unregistered foreign agent and making false statements to US federal agents.