How can one help guide a brother living in Dubai, who has strayed from religion, especially since he complains of falling into sins due to his loneliness and his work to support his family in Jordan?

You can invite your brother to guidance using the methods mentioned in Fatwa (definition) No. 36435. It is preferable to guide him towards the company of the righteous and to avoid bad companions, to increase in the remembrance of Allah and the recitation of the Quran, and to occupy his time with beneficial things. Marriage is also better for him. You can send him Fatwas No. 31607 and 41507. If you know righteous youth in his city, recommend him to them.