Can we use ionicons like we use
font awesome? or is there any workaround. Currently, they have the option to download SVG's but they are not opening in photoshop for me (I am using cs6).
Don't open an SVG in Photoshop - that will rasterize it. In some instances I've found that Photoshop can have problems rasterizing an SVG, especially a complex one.
Instead try placing the SVG using File > Place linked/embedded, or drag and drop the file into an existing document, where it will be converted into a Smart Object, and will remain a vector image. This certainly works in Photoshop CC. I don't have a copy of CS6 to test it.
If this still causes problems, perhaps try opening the SVG in Illustrator, and save as an AI file, then place the AI file as a Smart Object in a Photoshop document.