Billy Graham? When has he ever been accused of preaching a false gospel? never that I have heard.
Billy Graham didn't preach a false Gospel. However he is credited with suggesting folks make "a decision" and then parrot a "sinners prayer" which some folks construe as resulting in salvation. It replaced the doctrine of repentance in the pop-church, while the liberal wing of the church just quit preaching repentance during this apostasy, because when you do, the audience shrinks and church income drops.
As a popular mega-church pastor that I've heard says, after 50-100 folks step and parrot the sinners prayer, "Congratulations your name is written in the Lamb's book of life". Yet he has no more idea as to either the condition of their hearts, than he does God's judgments. Unfortunately some of those folks may think they've got it in the bag, and hardly think twice when they go home and jump right back into serial sin, like boozing.