This gentleman, with his hat and whiskers, looks to be a dapper – if middle aged – fellow. His vest seems a bit short to really disguise the pot belly, and the cut of his coat accents it also, but the clothing appears to be well made and fashionable.
The photographer was William Hirsch, who operated on both Blue Island Ave and 12th Street, in Chciago. He was in business from 1881-1900. I’m no good with men’s clothing, so I’ll peg this as the 1880s and leave it at that. If someone knows better, please enlighten us!