I need some help with analysing this differential amp
Watch these videos which explains the design of differential amplifiers

https://www.youtube.com/playlist?list=PLK2eyR1C9gjrMCVXRvKhY7CjNZYGCgMnY

I had designed mine recently and these videos really helped me to understand and design. There are certain analysis in the video lecture that explains about gain and relevant design criteria to achieve such a gain. The circuit diagram explained in the video are of a typical differential amplifier stage which is not exactly same as yours but gives you an insight on the design process. If you further have doubts comment here once again, I will help you as much as I know.