I'm unsure on the age of the shirt but due to the fit and the look and feel, it is an authentic Y2K Retro Original Xbox shirt - it includes official Xbox tag

Men's Size Large 

Material: 100% Cotton

Measurements:

Arms: 14" (Elasticated)

Pit to Pit: 22"

Chest: 44"

Neck to Waist Length: 25.5"

Sold as seen 

I know these sorts of shirts CAN be worth a lot of money. I may reduce price over time and I will leave offers open.