The get together took place a day after the May 2016 fight that reportedly ended the couple's marriage.
Franco will be subpoenaed by Depp's legal team for questioning, according to The Blast editors, who have also obtained the video footage of the "127 Hours" star and Heard in an elevator of the Los Angeles apartment building Depp and his wife shared.
Franco is reportedly being called as a "witness," and he will be asked if Heard discussed the alleged fight, or if he saw any injuries to her face.
Depp is suing Heard for defamation after she referred to herself as "a public figure representing domestic abuse" in a Washington Post article last year (2018). He claimed he had been defamed in the piece, even though Heard didn't name him, stating it suggested the actress was a domestic abuse victim and he "perpetrated domestic violence against her."
The couple split in 2016 after Heard accused Depp of being abusive throughout their 15-month marriage.
Depp has always denied her claims that he was violent towards her and insists he has proof that all of her allegations against him are bogus.
A Virginia judge has set a trial date for February 3, 2020 and estimates the defamation case will last 12 days.