Can a person withdraw from people because of their failure to repent from backbiting and slander, and because their gatherings are filled with envy, falsehood, and lies? And is visiting one's paternal uncle considered maintaining kinship ties?

A Muslim should not attend gatherings of evil unless it is to denounce it. If the people do not respond, he should distance himself from them. If he sits with people committing sins, yet he is forbidding the sin and calling to good, then there is no blame upon him. Allah Almighty said: "And when you see those who engage in [blasphemous] discourse about Our verses, then turn away from them until they enter into another conversation. And if Satan should cause you to forget, then do not remain after the remembrance with the wrongdoing people. And there is no accountability upon those who fear Allah regarding them, but [only] a reminder that perhaps they will fear Him." (Al-An'am: 68-69). As for visiting the paternal uncle, it is among the highest forms of maintaining kinship ties, because the paternal uncle is like a father.