I'm a former anti-Zionist Jew, I still have many close Jewish family and friends who are heavily involved in anti-Zionist activism, with JVP and if not now, etc..
On the low end of polls I've read in the past few years a Gallup review of US Jews found "about nine in 10 American Jews are more sympathetic to Israel than to the Palestinians" and "95% of Jews have favorable views of Israel, while 10% have favorable views of the Palestinian Authority."
Polls of how many American Jews are Zionist are not generally conducted, since no one agrees on exactly what constitutes Zionism. For instance I oppose settlements and Bibi, but call my self a Zionist because I believe Jews and Palestinians should have the right of self determination in there respective states.
While I will not attempt to pin down a definition of Zionism, I think we can all agree a Jew who has a overall favorable view of Israeli is not going to identify as an anti-Zionist. I have met almost all the actively anti-Zionist Jews in a small city at numerous rallies and Sabbath dinners and not once have any of them expressed that their view of Israel is favorable.
In theory anti-Zionism is not antisemitism, however if someone told you they were not anti-black they just disliked black people who did not vote for Trump, what would you call them?
It is tragic that I had to write this from a throwaway, but I do not want my career to be damaged by a public association with Zionism.