On college campuses, about 90% of the demonstrations were over issues like dormitory curfew hours or campus dress codes (still had 'em back then. My first year in college, women were not allowed on campus wearing pants, or anything other than a dress.)
As far as influencing the public against the war, the hippies actually had a negative influence. They were colorful and produced most of the good music of the time, but they were also a laughingstock, the butt of jokes of Rowan and Martin. No one took them seriously.
Public opinion turned against the war as a direct result of LBJ dropping out of politics after the Tet Offensive. He announced troop withdrawals and peace negotiations, an unmistakable admission of failure. Even Nixon ran on a 'secret plan to end the war'. Note, not a plan to WIN the war, just a plan to end it. That's what the public wanted. That's what they got. When funding was cut off, nobody even cared about Vietnam anymore. The 'ME' generation was getting in gear, and hippies were dropping back in to society in droves.
My summation: the 'mass' demonstrations, the hippie thing, violent campus unrest all PERPETUATED public support for the war effort, galvanizing the hard hats and uncorrupted sons and daughters all across America. But leadership at the very top failed. First they ask you to risk your life for a cause, then suddenly that cause is 'negotiable', and there's still a draft. So Kissinger takes over, for all intents and purposes, the management of the war effort. He invades Cambodia, inflames the situation there to the point of driving Prince Sihanouk from office while utterly failing to cut the Ho Chi Minh trail. Then he tries to invade the DMZ, another dismal failure. Then prolongs the war with mass bombings that almost make Hanoi cry 'uncle', but stops short, caves in to every NV demand, and gets a Noble Peace Prize for his valiant efforts. That's how the war was lost. Not Joan Baez, not even Jane Fonda. Just bad leadership. Hippies on the street? Yeah, real influential, very well financed, lots of media access... what I mean is, are all you hippie-bashers serious?
I hate hippies, said in my best Cartman voice.