Matthew 24: 34: Verily I say unto you, This generation shall not pass, till all these things be fulfilled.
Jesus told His disciples of the signs that would precede His coming and the end of the world, and further stated that the generation which saw the fig tree put forth leaves would not pass before all the signs had been fulfilled. Israel is represented by the fig tree in the Bible, so when Israel returned to nationhood in 1948, the Jews that saw this momentous event happen would not completely die out before everything had been fulfilled that Jesus spoke of.
In one sense a generation is considered to be about forty years, however, the year 1948 to the year 2023 far exceeds that number, so when Jesus is speaking about a generation in Matthew 24: 34, He is speaking on a much different plain than a forty-year generation. When we consider the lineage of Jesus in Matthew 1, it is recorded as the generations from Abraham to Christ, and divided into three units of fourteen generations. These three groups of fourteen generations are not divided into tidy 14×40 year units, for the lifespans of those named in the lineage varied greatly, and whilst one generation was still alive, the next generation had obviously been born, thus a son, his father, his grandfather and his great-grandfather etcetera can all be alive at the same time.
It is the Jewish people who were alive at the birth of Israel as a nation in modern times that Jesus is speaking of; it is they who would not completely die out before all the signs that Jesus spoke of have been fulfilled. A Jewish baby born in the year 1948 would be 75 years old today, and many more Jews born before 1948 are much older than that today, but they are alive nonetheless, and they will not all die out before everything that Jesus spoke of has been fulfilled.