The Scenario that seems most likely to me is that the Yom-Kipur war of October 1976 would be called of and delayed until Pesach 1977 (2 to 10th April) If this time was used for:
-training
-integrating smokescreens into the tactical repertoire of the syrians. (A big reason for the syrian failure in the Golan heights was Attacking over overseeable terrain against entrenched defenders)
-aquisition of additional SAM-Systems
Also for Pesach more people travelling to visit the family to celebrate, whilst on Yom Kipur you have the roads are free, the Soldiers and Reservists are either at home or in the synagoge close to their home, allowing for faster alerting and mobilsation on this date.
If then they still achieve suprise, Egypt doesnt leave SAM-Cover and better combined arms coordination exists (artillery deliverd smokescreen against entrenched defenders), the Arabs have a chance.
When then the Israelis botcs the depolyment of their nukes (most stupid scenario using it against an enemy capital instead of the enemy army, more likely they miss a tactical target by failing a toss bombing attempt. see also: https://en.wikipedia.org/wiki/Toss_bombing and https://tvtropes.org/pmwiki/pmwiki.php/Literature/TheSumOfAllFears).
If the Israelis use their nukes, their is a high chance of retaliation against civilians (though civilians in this war are genrally fucked if they meet hostile forces. Even if the IDF is said Hostile force, if they have to carry out Counterattacks into Syrian/Egyptian Mainland, especialy if the Arabs had a go at the Israeli Civilians beforehand.)
You mean delaying it from October 1973 to April 1974, right? Either way, while not impossible, it would be unlikely that an Israeli defeat in the Yom Kippur War would wipe Israel off the map. Egypt’s primary motive was to regain the Sinai peninsula from Israeli control, not to make it cease its existence.