Does tahini have the same taste as sesame oil?

Depends. Some sesame oil is toasted and has a distinctive flavor.

That was supposed to be "presume"

As Monita explained, Tahini is pasty and thicker. For this recipe, I think you could get away with using sesame oil as a substitute but I would start with only 2 tablespoons of sesame oil, since it already has 2 tablespoons of olive oil.
Just a note that some Tahini preparations are not au naturel, they come with lemon and garlic added. This recipe seems to preume you're using plain Tahini paste as they have you add the lemon and garlic. (Definitely add those as per the recipe!)

Tahini has a sesame taste but different texture. Tahini is more paste-like