No, the little black flies in the soil are fungus gnats. If you type that into the search box at the top left of page , you will find lots of information about them. Their larvae are in the soil and can eat plant roots , but they are not leaf eaters .
It looks like you have a bad case of slugs or snails . You will never see them in daylight , but if you come out late at night or very early in the morning with a flashlight , you will find them .
Looking at the top picture, your tomato plants weren't doing very well even before they were attacked by slugs.
It looks like you have two plants tied together to one stake, which will never work. And they look pale and spindly, suggesting they are not getting nearly enough light. Are these plants on a balcony? Which direction does the balcony face?