I'm sorry, exactly what in Rev. 7:14 indicates it means here and now of all times?
Because Revelation was Not written for 1st century people.
The great tribulation of Rev. 7:14 was Not for the 1st century.
The great crowd of people mentioned in verse 9 are living people, alive on Earth.
Just as the figurative 'sheep' mentioned at Matt. 25:37 are 'living people alive on Earth' at Jesus' coming Glory Time - Matt. 25:31-34.
So, the already dead are not saved /delivered / rescued through the coming great tribulation of Rev. 7:14 but living people on Earth are.
Those of us who are alive at Jesus' coming can remain alive on Earth and live through the coming great tribulation and be here on Earth to see calendar Day One of Jesus' Millennium-Long day of governing over Earth for a thousand years with the opportunity to live forever on Earth.
Jesus Not only offered everlasting life in Heaven for some, but everlasting life on Earth for the majority of people - Matt. 5:5; Psalms 37:9-11; 22:26