I don't think anyone can put a number on all Israel will be saved.
Certainly the beast-king and the false-prophet will not be saved and both will be Jews.
All Israel will be saved is talking about the Jews going through the great tribulation will turn to Jesus in the middle of the seven years. They turn to Jesus and the gospel of salvation in Revelation 12:!0.
The scripture below clearly states (Israel/Jews) will not obtain salvation, only the elect will obtain, those who God chooses by foreknowledge
The Elect remnant Jew will be saved and added to God's Israel the Church upon earth, Israel of the flesh will be blinded
Romans 11:2-8KJV
2
God hath not cast away his people which he foreknew. Wot ye not what the scripture saith of Elias? how he maketh intercession to God against Israel saying,
3 Lord, they have killed thy prophets, and digged down thine altars; and I am left alone, and they seek my life.
4 But what saith the answer of God unto him? I have reserved to myself seven thousand men, who have not bowed the knee to the image of Baal.
5 Even so then at this present time also
there is a remnant according to the election of grace.
6 And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then it is no more grace: otherwise work is no more work.
7 What then?
Israel hath not obtained that which he seeketh for; but
the election hath obtained it, and the rest were blinded.
8 (According as it is written, God hath given them the spirit of slumber, eyes that they should not see, and ears that they should not hear;) unto this day.