@aban
سوال 4) If the answer is no.1, the sentence will be translated like this: "They CLAIM that he HAS an influence on many other chefs; but here we cant see the present form of the sentence, so I think choice no.3 fits better
سوال 5) If yu read the sentence once, choice no.3 fits the best since the sentence must be in passive voice
سوال 6) Its very common to use the structure Has been, so choice no.3