Is the age of grace predominantly Gentile?

Yes. The present age of grace is predominantly Gentile, described as Gentile only with some Jewish exceptions. Within it, God preserves a remnant of Jews who believe the gospel of grace, chosen according to election, not law or Judaism. They are a small percentage.

Les explains that throughout Scripture God has always kept a remnant, as illustrated by the broad way and the narrow way. Paul writes that in this present age of grace, the age is predominantly Gentile—Gentile only with some Jewish exceptions—yet there remains a remnant of Jews who believe the gospel of grace. This remnant is according to the election of grace, not law or Judaism. Les also mentions a book of testimonies of Jews who became believers, calling it thrilling and noting they are very few, like the 7,000 in Elijah's day.

Romans 11:5

Even so then at this present time also there is a remnant according to the election of grace.

What is the makeup of the Jewish people in this age of grace?

In this age of grace, the Jewish people are largely outside the gospel, with only a small remnant—a small percentage of Jews—becoming believers in the gospel of grace. This remnant is chosen according to the election of grace, not law or Judaism, while the age itself is predominantly Gentile with some Jewish exceptions.