No, I don't believe speech can be violence. Screaming "N____" at black people is a shitty thing to do, but not violence. Murdering people is violence. Stating that you will demonize, illegalize, and murder people if they get power is a good argument to make sure they don't get power, but it is not violence.

There is a fairly clear dividing line between "violence" and "not violence": "Did you directly cause physical harm to another person?" Punch someone? That's violence. Shoot someone? That's violence. Throw someone to the ground? That's violence. Run over someone with a truck? That's violence.

Call someone nasty names? That's a shitty thing to do, but it's not violence even if it hurts emotionally; you are completely in control of your emotions, and you can also choose to disregard anything anyone else says. Say that you will inflict violence on someone in the future? That is also not violence, though it is perhaps a reason to be extra vigilant and take measures to prevent that violence from occurring. Incite other people to violence? They are guilty of violence, but you are not (incitement to violence is its own crime, and one that is intentionally very narrowly defined).