Is that an actual quote?
YES.
One of the leaked DNC e-mails references it.
It wasn't an e-mail from Clinton to Brazille.
She said it right to her face.
Here is the full quote:
“If that fucking bastard wins, we all hang from nooses! Lauer’s finished… and if I lose its all on your heads for screwing this up. You better fix this shit!” - Hillary Clinton screaming at Donna Brazille on October 17 2016.
Yes, the Lauer that Hillary Clinton is referring to is Matt Lauer, former co-host of NBC's Today show. She felt he went after her and had been rough in a recent interview.