Are you gay if you are transgender?

No,not techinally. When you are a full trans boy or girl, you are not classified as gay. If you are a FtM, and are interested in boys afterwards, then yes, you are classified as gay or bisexual, since you are now a boy. On the other hand, if youre a MtF, and find interest in girls, you may be either rbisexual, or lesbian, due to that now you are a female.

No, being transgender no more makes you gay than being cisgender makes you straight.

A persons sexuality is different to their gender, a trans person can be straight, gay, bi, pan, asexual, or any other variation in sexuality - it's all down to the individuals sexuality, not determined by their gender.