90 per cent of the Soho strip clubs have gone in the last 15 years. The brothels are still there but they are all first floor so most tourists don't even see them. There is zero street prostitution in Soho, and indeed most of London. Soho is primarily a bar and restaurant destination now.
For odd reasons, the legal lap dancing / strip clubs are not in Soho at all, probably because they are aimed at the office market and there isn't a high concentration of white collar workers there.