Yes a 7 month old baby can eat Gerber puffs.
Some 7 month old babies are ready to eat things such as Gerber puffs and some babies may not be ready for Gerber puffs or other similar foods until 9 months old.
But you certainly can try feeding your 7 month old baby Gerber Puffs and they will usually like them and eat them just fine.
My nephew started eating Gerber Puffs when he was 7 months old and he's now 18 months old and still enjoys them.
I buy Gerber Puffs for him to keep at my house when I babysit him for his parents as he loves them.