Is it permissible for a young man to receive assistance from his friend's Zakat, knowing that his monthly salary is insufficient, he is single, supports his family, and his salary is below the government-determined poverty line?

As long as your salary does not cover your needs and the needs of those whose maintenance is obligatory upon you (such as parents), you are eligible to receive zakat funds. In addition, the government considers anyone earning a salary like yours to be poor, and they are more knowledgeable about the costs of living.