Will people who are left behind after the rapture have another chance to accept Jesus as Savior?
That depends on whether they will have rejected the Gospel before the rapture or not. 2 Thes. 2:9-11 says those who have refused to love the truth and be saved will perish but it doesn’t specifically include those who had not made a decision either way.
And Rev 7:9-17 describes a large multitude of people from every nation, tribe, people, and language arriving in Heaven. I believe these are post rapture believers from all over the world who will have been martyred for their faith during the first half of Daniel’s 70th Week and aren’t part of the Church. We know this because the Church will be raptured before the 70th Week begins, and the destiny of these martyrs is to serve God in His temple but they’re never called priests. Therefore they can’t be the Church who are both kings and priests.