Did Methuselah really die in the flood year?

The arithmetic is a straightforward addition. Every fathering age from Adam to Noah is given in Genesis 5; Noah's age at the flood is given in Genesis 7. Working from the MT:

Methuselah was born at year 687. He lived 969 years (Gen 5:27, MT). He died at year 1656. The flood began at year 1656. The convergence is exact, and every number that produces it comes from the text (lookup verse Gen.5.3, Gen.5.6, Gen.5.9, Gen.5.12, Gen.5.15, Gen.5.18, Gen.5.21, Gen.5.25, Gen.5.28, Gen.7.6). The narrator does not remark on it.

Does the name encode it?

Methuselah (H4968, מְתוּשֶׁלַח) is often read in popular treatments as muth-shelach — "his death shall send" or "when he dies, it [the flood] shall be sent." On this folk etymology the name is a walking prophecy across the longest life in the canon. The lexicographic reading, BDB's entry, is different: "man of the dart," parsing the consonants as math (H4962, "man") + shelach (H7973, "missile, weapon"). The Hebrew consonantal text — mem-tav-vav-shin-lamed-chet — does not decide between the two because the distinction hinges on how you vocalize meth-/math- (man) versus muth- (death). BDB marks the entry with a question mark over both. The folk etymology is not impossible — Hebrew name-wordplay regularly trades vowels — but it rests on a vocalization not preserved in the MT's pointing.

What is indisputable is the arithmetic. Whether or not the name predicts the flood, the MT's numbers place the longest antediluvian life's end at the flood year. The point does not require the folk etymology to stand.

The LXX complicates the picture

The Septuagint preserves a different set of numbers. LXX Gen 5 adds 100 years to the fathering ages of the first five generations (Adam through Mahalalel), shifting births later. LXX Gen 5:27 keeps Methuselah's total lifespan at 969 years — identical to the MT — but on LXX cumulative arithmetic, Methuselah's birth falls around year 1172 from creation, placing his death around year 2141. The LXX flood arrives around year 2242. The simple arithmetic suggests Methuselah survives the flood by roughly a century on LXX numbers, which is why ancient Jewish chronographers — and some LXX manuscripts in the Lucianic recension — adjust his figures specifically to resolve the paradox.

The Samaritan Pentateuch takes a third path. It lowers Jared's fathering age to 62, Methuselah's to 67, and Lamech's to 53 — producing a shorter overall antediluvian span of roughly 1,307 years — but internally consistent: Methuselah still dies in the flood year on SP arithmetic.

Three witnesses, three sets of numbers. Two of them (MT and SP) preserve the Methuselah-at-flood feature. One (LXX) does not, and the scribal tradition struggled to fix it. The canonical Hebrew text the church has received is the one where the longest-lived man's death converges exactly with the year the waters rose.