I'm currently becoming a fitness professional and looking to open a gym in near future and in every gym there is music and people expect a gym with music system. Although my aim is to open a gym but will playing music in it will be haram for me? And earning through that gym also will be haram?
Please suggest what you think is right

Yes playing music which is haram is forbidden. Maybe you can play music which is not usually used in gatherings of haram, eg nasheed perhaps.