Faim is more like hunger (although I have hunger doesn't look idiomatic) so only J'ai faim is valid, je suis faim is impossible.

I'm very hungry would be J'ai très faim. You might also say Je suis affamé which is slightly stronger than I am very hungry.

Faim is more like hunger (although I have hunger doesn't look idiomatic) so only J'ai faim is valid, je suis faim is impossible.

I'm very hungry would be J'ai très faim. You might also say Je suis affamé(e) which is slightly stronger than I am very hungry, more like I'm starving.

Faim is more like hunger (although I have hunger doesn't look idomatic) so only J'ai faim is valid, être faim is impossible.

I'm very hungry would be J'ai très faim. You might also say Je suis affamé which is slightly stronger than to be very hungry.

Faim is more like hunger (although I have hunger doesn't look idiomatic) so only J'ai faim is valid, je suis faim is impossible.

I'm very hungry would be J'ai très faim. You might also say Je suis affamé which is slightly stronger than I am very hungry.