discuss victorian age with reference to Joseph Andrews?

This is such a broad question. One can consider the corruption and role of the church, city life vs country life, class system....If you need one, I'd consider class system. The Victorians were all over that one!

Joseph Andrews is full of class distinctions and concerns about high and low birth, but Fielding is probably less interested in class difference per se than in the vices it can engender, such as corruption and affectation. Naturally, he disapproves of those who pride themselves on their class status to the point of deriding or exploiting those of lower birth: Mrs. Grave-airs, who turns her nose up at Joseph, and Beau Didapper, who believes he has a social prerogative to prey on Fanny sexually, are good examples of these vices. Fielding did not consider class privileges to be evil in themselves; rather, he seems to have believed that some people deserve social ascendancy while others do not. This view of class difference is evident in his use of the romance convention whereby the plot turns on the revelation of the hero’s true birth and ancestry, which is more prestigious than everyone had thought. Fielding, then, is conservative in the sense that he aligns high class status with moral worth; this move amounts not so much to an endorsement of the class system as to a taking it for granted, an acceptance of class terms for the expression of human value.