Short answer
No, avoid feeding gravy to kittens. Even small amounts often contain onion or garlic, which damage young cats' red blood cells. Watch for pale gums or lethargy over the next day, and skip the vet unless you see these signs. Stick to kitten-formulated foods for now.
Gravy — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
Almost always built on onion and garlic stock. This is a common allium exposure.
The full verdict, portion guidance and serving notes are collected on the Gravy food facts page.