You cannot exactly convert GIF images to XLSX. However you may import images in several graphics format (PNG, GIF, JPG) to a spreadsheet as a object. Probably what also various converters offer, so you would get a blank spreadsheet with inserted picture inside in the first list.
Some OCR tools also allows you to "read" images and import the data from them to spreadsheets. But that is something only dedicated OCR programs are capabale of.