It would win a solid majority in Israel.
Depends if Arabs turnout is over 30%.
58-42 yes I would say, with with 68-32 among Jewish voters.
But that really depends if it's a referendum on SSM or civil unions in general
I find it hard to imagine a large Arab turnout for this, especially if their politicians don't mobilize them.
To be honest, I'd be very interested in seeing this referendum playing out in Israel. It would expose the homophobes in parties like the Joint Arab List and the Jewish Home, despite their leaders trying to appear modern and friendly.