The confusion about which came first, the Gilgamesh Epic or the Bible, centers on which dating method you use and your worldview. The Egyptian chronology is littered with problems as to accuracy.
If you've studied the history, rather than simply read about it, you already know that Ptolomy II commissioned a priest named Manetho to compile a history of Egypt. You should know that Manatho's chronology is known to be inaccurate. Moses has finally been found in the 12th Dynasty, for example, rather than the 18th where they were looking, and knew the Bible to be in error before. Because Manetho’s history contradicts actual Egyptian records from the time of the pharaohs, historians should not consider Manetho’s history authoritative.
Perhaps the proto-Hebrew texts dating back to the 11th century BC? That and other evidence suggest the Bible was written as events were happening since the Davidic period... Those same texts explicitly refer to the Books of Moses pushing the books of Moses back to 1450 BC.
Parallel historical accounts are found in more than 500 civilizations around the world, many with no clear connection. Independent from the Bible, Noah's grandson Kush is specifically named as a post flood king in the Sumerian Kings list.
Then you have non-textual physical lines of evidence indicating a global event about the time (based on genealogies) that are consistent with the flood or the likely aftermath.
While a study of the Sumerian list is a fascinating journey in discovering the way Sumerians looked upon their ancestry and how their numeric and commercial systems worked, the quality of the biblical text is distinctly superior in both completeness, information, and spiritual and moral quality. The biblical text does not reflect a borrowing from an inferior text. If anything, the very mention of this kings list that matches so closely to the biblical account is a confirmation of biblical authenticity.
The Near Middle Eastern Flood epics have three main versions: the Sumerian Epic of Ziusudra, the Akkadian Atrahasis Epic, and the Babylonian Gilgamesh Epic. The Gilgamesh Epic is the most complete with 12 tablets decipherable and the eleventh tablet with the most complete flood account of the three versions. These flood epics reveal many internal inconsistencies, which rule them out from being the source of the Genesis text.
As to similarities with Gilgamesh and the Bible other than a flood (local in the epic) and a boat (small in the epic) there really aren't any! There are far more similarities in the Sumerian Eridu, Atra-hasis and the Shuruppak than in the Epic of Gilgamesh.
Actually the Epic of Gilgamesh dates to about 1050 BC.. References to the Books Moses wrote date to the same period about 1000 BC indicating first there were indeed texts written by Moses, and that those texts were known and fairly widely distributed by that time. If we examine the Genealogies we find that those texts by Moses had to be written no later than 1450 BC a full 400 years before the Epic of Gilgamesh.
It is not difficult to rule out the Ancient Near Eastern mythological texts from being the source of influence for the account of Genesis. While Genesis is reliable, they are not.
Foolish men have been attempting to take apart or add to the Bible for millennia, yet it still stands, unchanged truth, more verified by time. By now, we should "know" what the Bible says. Of the top ten Hebrew departments in major cities around the world, there is no debate over what Genesis 1-11 of the Bible "says." Young Earth, literal six day creation. All agree, the narratives of the Creation event and Noah's Flood in Genesis are both literal events of history, documented in technicolor.
Is the Bible a copy from Paganism
http://plottingeoe.com/blog/is-the-bible-a-copy-from-paganism
Can we believe what the Bible says?
http://plottingeoe.com/blog/can-we-really-believe-what-the-bible-says
Seven Evidences for a Young Earth
http://plottingeoe.com/blog/seven-evidences-for-a-young-earth
Is Noah's Ark a Fairytale?
Why don't Christian fundamentalist just give and admit that Noah the Ark is just a made up fairytale?
http://plottingeoe.com/blog/is-noah-s-ark-a-fairytale
Dating the Bible w Egypt pyramids and Gilgamesh (also ice cores)
Did The Biblical Flood Happen?
http://plottingeoe.com/blog/did-the-biblical-flood-happen
Geology of Grand Canyon & Noah's Flood
In what ways do you justify that the Earth is some 6000 years old?
http://plottingeoe.com/blog/geology-of-grand-canyon-noah-s-flood
How many years ago was Noah's flood? 4,400 year ago, or 5,000 year ago?
https://answersrip.com/question/index?qid=20160311171338AA8ido3&page=2
"The evidence is all around you. Our entire world is the work of God" - Is this good evidence for Christianity?
What will determine that you know this … or not?
http://plottingeoe.com/blog/what-will-determine-that-you-know-this
Addendum of Evidence in the Bible
http://plottingeoe.com/blog/addendum-of-evidence