I know that all Israel will be saved but I want to know what will happen to the gentile children of Jews , I understand that they are not Jewish but they have Israelite blood on them will they also be saved ?
Unfortunately, the child of a Jewish man that was born from a non-Jewish mother, is not considered Jewish. This is one of the terrible ramifications of intermarriages.
As a side point, the idea of being “saved” depends on each person and in accordance to their actions in this world. A gentile that keeps the seven Noahide laws, and acted righteously will be rewarded in the world to come. Additionally, even a child born from a non-Jewish mother, can always become a ger, and “convert”. Then the child will have all the benefits of being Jewish, plus he will be considered extra special to Hashem, because Hashem loves those who specifically chose Him, even though they didn’t have to.