Summary
The Wizards signed the overseas veteran last offseason to provide some depth at forward, but Gill was unable to make much of an impact, only playing 173 minutes of non-garbage time, according to Cleaning the Glass. The Wizards already have a good amount of depth at forward with Deni Avdija, Rui Hachimura, Davis Bertans, and also started giving Chandler Hutchison some minutes after acquiring him at the trade deadline.
 
Statistically, nothing really pops out for Gill, as he shot poorly from outside, albeit on a small sample size, and had poor rebounding numbers. Gill did seem to show some overall feel and a knock for making the right play, but I don't think Gill is anything more than replacement-level, at best. Gill is already 28, so there's also not a ton of upside or expectation for improvement.
 
Cap Considerations
Gill's $1.5 million salary for 2021-2022 is non-guaranteed, and if he is waived he will become an unrestricted free agent and the Wizards will have no form of Bird rights on him. If he is waived, any team could claim him off waivers since he is on a minimum contract.

If Gill becomes a free agent, other teams will have multiple ways to sign him as even teams without cap space could possibly use either of the Non-Taxpayer MLE, Taxpayer MLE, or possibly even the Room MLE to sign him. If Gill is waived and clears waivers, his value will be low enough that he would likely only have offers for the minimum.