Both experiences would help your future employment. I'd encourage grad school unless the Amazon job was something particularly special and perfect. Amazon might be willing to defer your job for a year while you get a MS.

Will your grad school work be done in a year resulting in the equivalent of an MS, or are you looking at a phd or longer timeframe? Shorter timeframe is better, then you can torture yourself again by looking for a job after the MS. Are you studying something you like, is it relevant with today's AI craze or not? Do you feel excited and passionate, do you care about getting an MS?

No one can predict what the job market will be in a year, will we be in a widespread depression? More likely it will be like today, economy ok but unclear future as the world muddles through. Even if you go there now, amazon could lay you and your division off and you'd be scrambling for a new job to stay in the US (presuming you aren't a us citizen). Or maybe your grad school work would make you more employable (or you work on something at amazon that is hot), depends on the area.

I was excited to go to grad school and was glad I went because my undergrad wasn't an especially great school. Then I went to big tech after grad school years passed. If you are excited about grad school and it's not a many year commitment then I'd go that. If you are hot to come to Seattle or where-ever, and you are paid enough to live there, and/or Amazon offers you a job working in something that excites you then do that. No easy answers in life.

This feels like a wishy-washy answer but everyone has to decide for themselves.