The way statistics work, 1000 people is more than adequate for a population the size of Israel. It’s honestly overkill, if anything. The real question is “are the respondents a representative sample?” That is, is the way you chose who to question and how to question them introducing any systemic bias in your results? For this survey, if everyone lived in the West Bank, that would be a clear source of bias in the data. But if people are randomly selected by, say, phone number, then you would have to worry about more subtle biases before agreeing that the data is sound.
The way statistics work, 1000 people is more than adequate for a population the size of Israel. It’s honestly overkill, if anything. The real question is “are the respondents a representative sample?” That is, is the way you chose who to question and how to question them introducing any systemic bias in your results? For this survey, if everyone lived in the West Bank, that would be a clear source of bias in the data. But if people are randomly selected by, say, phone number, then you would have to worry about more subtle biases before agreeing that the data is sound.