God created the universe in six days. Man was on the sixth day. The Bible follows the lineage of Adam to Christ putting the earth at a young 4000-6000 years old. God came to earth to live among us and save us, and he will return for those who trust in him. Eternity will follow - with him or apart from him. Satan would have you believe anything else but this. Do not be fooled.
Thank you for your attention to this matter.
So...how many years is each day of six days?
Respectfully, I don't see where the Bible explicitly says that the earth was created in six calendar days, or that creation occurred roughly 4,000 years before Christ. Us Christians don't have to win the argument over the age of the earth for us to be literal Bible believers.
The Hebrew word yôm is what's translated to "day" in Genesis 1. It has multiple literal meanings, including a 24-hour period and and an undefined era (definition # 5 in the link). Similarly for "evening" (Hebrew ʿereḇ), which in Psalm 30:5:
For His anger is but for a moment,
His favor is for a lifetime.
Weeping may endure for a night,
But a shout of joy comes in the morning.
Obviously the "night" is not a brief portion of a 24-hour day, but a period of time. The same for "morning" (Hebrew bōqer) being used sometimes as the start of daytime, but in Zephaniah 3:5 used as the start of an era of God's judgement. These are just some examples of how the Hebrew words in Genesis 1 for day, evening, and morning are sometimes used elsewhere in the OT to not refer to 24-hour period time constructs. Thus, we should be open to the possibility that the Genesis 1 creation account is talking about 6 long eras. (Note I said "possibility", I can't definitively say it is talking about long eras and not 24-hour days. Those same words are sometimes used to denote 24-hour days.)
The same for the lineage argument and how the Hebrew people wrote lineage with obvious gaps. The gaps aren't evidence of lies, the Hebrew culture simply allowed it be correct to say that my great grandpa "begat" my son if the one writing it deemed that both I and my father weren't worth mentioning. As an example, compare Jesus' lineage in each of the Gospels. The differences between Matthew's and Luke's lineages for Jesus is partly royal vs birthly lineage, and partly a difference of which ancestors were worth mentioning and which not worth mentioning. (42 generations in Matthew vs 77 generations in Luke). With that in mind, who knows how many of Jesus' ancestors both of them ignored? The same for the ancestors from Adam to Noah, and Noah to Abraham. From a purely exegetical interpretation (meaning no modern or personal bias), we simply don't know how long those eras were. Adam could have lived a thousand years ago, hundreds of thousands of years ago, or even millions of years ago (looking just from the Bible).
So if you and I want to win the argument against people pushing the evolution/natural selection narrative, don't get sucked into an age of the earth debate. It's simply not explicitly indicated in the Bible IMHO, thus not an argument we have to win to promote believing in the Bible's creation account. Focus on the definite interaction God had with creation. Focus on things like natural selection being thrown a curve ball by the Cambrian Explosion. Focus on all the things in nature and the cosmos that demand fine tuning for things to work for advanced life to exist. If you do those things, you point out that it requires a lot of religion to believe we got here through a bunch of freak accidents. Then point out the sequence of events in the creation story. Archaeologists agree that life came into existence in that sequence -- that can't be coincidence. Point out that Genesis 2 says that God made Adam from the dust of the earth --- written centuries before the ancient Greeks said that man was made from the dirt "element" and before we say with our periodic table that we are carbon based organisms -- that can't be coincidence. Nor can it be a coincidence the Garden of Eden's Tigris and Euphrates rivers is the location of the Fertile Crescent.