I think that would be right around the cut off, most sources I'm seeing online have millenials going up to and including 1996, which would be this supposed person's likely year of birth
I think for Zillennials it depends on their upbringing. People from poorer families will most likely identify more with Millennials while rich kids would be more strongly tied to Gen Z due to the technological gap.
Can confirm. My friends and I all right at that Zillenial transition point, and friends from well-off families identify with and behave more like Gen-Z while other friends from less affluent families fall more in line with Millennials.