If Eli Manning needs some advice on how to handle a Hall of Fame slight -- Antonio Gates is offering it up!

The legendary Charger -- who was inducted into the 2025 class last week after being snubbed for the 2024 one just 12 months ago -- told TMZ Sports out at the Super Bowl in New Orleans that while he's sure Eli's feeling heartbreak right now ... the former signal-caller just needs to stay positive.

Gates told us that after he was shockingly barred from getting a bust in Canton ... he headed into the ensuing year focused on being "the best version of me" -- and he thinks that attitude helped him get in this go-around.

Gates also said leaning on his faith certainly didn't hurt, either.

Fortunately for Manning, it seems he's already put some of the ex-tight end's guidance into practice ... because when we caught up with him on Bourbon Street just hours after the '25 class was revealed, he didn't seem to be sweating things one bit.

Eli, of course, will have another go at things in 2026 ... and while the competition is stiff -- Larry Fitzgerald, Jason Witten and Drew Brees will all be eligible then -- Gates and a host of others sure appear to think he's in line to get the happy call.