I believe Vietnamese speakers use chicken only to refer to the fowl and the food.
No, this word is not like imply cowardice in English. In Vietnamese, if you say someone like chicken "gà" it means this person always think for the problem or something very simple, not understand the reality of the problem. This word can also mean the skill of that person to solve the something problem is very bad, not enough to resolve. So it is only used for your best friends, it is not polite when said that to other people.
When I was growing up in the south. 'Mày gà quá đi' was used among the kids. In my case. It means, you're so lame
He is stating that he is not a chicken, rather than him not liking it. This sentence is only about whether this individual is a chicken or not. Không thích means do not like, which is a different meaning.
I think Heysoos1's question was, why is it not "Tôi không là một con gà.", but instead không phải là. It's indeed irregular and a special case in Vietnamese, that has to be remembered.
Không phải + noun + là... = not + noun + to be verb (is/ are/ am...)
Không + thích ....= don't + like
In the grammar notes, it indicates that "không phả là" is used in the case of identity, and with the "to be" verb. In this case, there is a negation of the identity of being a chicken.
In other cases, "không" is used without "phải là" in all other cases (that are non-identity).
Thich is "like" as in "I like apples/Toi thich trai bom" Phai can mean "right" both as "correct" or in it's directional sense "turn right/queo tay phai"
I am still wondering about "không phai là" vs. "không là" vs. "không"... what are the meanings? Vietnamese. In which instances would you use each?