In the Bible how long did God say man could live on earth?

If they exercise faith in the ransom of Jesus (Jehovah God's son), people are able to live eternally. (John 3:16) This is part of Jehovah's original purpose for the Earth, which will be fulfilled in the future. (Psalms 37:11 & 29) This also explains why Jehovah "put eternity" in the hearts of people-He created them to live forever originally.

When Adam and Eve sinned, they became imperfect. After that they had children, which could only be imperfect just like them. (Romans 5:12 & 14) However, thanks to Jesus giving his life, he was able to get mankind another chance to have what they lost-eternal life. (Romans 5:18)

(New World Translation of the Holy Scriptures)