Answer:
If Jay were interested in video games, he would enjoy this gift.
Explanation:
"If Jay were interested in video games, he would enjoy this gift."
The above sentence is the correct form of sentence. Here the verb 'were' is in the subjunctive form. It is not in the indicative form.
A subjunctive is considered a special verb form. It is grammatical mood. It generally represents or expresses the wish or the attitude of the speaker towards  something imagined or desired.
