Unfortunately the answer is highly variable based on the applications you install on the Hosted Application Server (HAS) image and the cpu / memory requirements of each user session. Memory is the more common restricting factor.
Most administrators go through a tuning process during a pilot to assess how to set this parameter.
The Hosted Application Server comes with 8vCPU and 16GB of vRAM.
Once you subtract 2GB of vRAM for the core OS use, that leaves about 14GB of memory for user sessions.
Suppose that you have a fairly simply application set with memory requirements topping at 512MB per user session, , You can expect to support up to 28 users per HAS. This might be the case simple task worker / data entry applications.
Medium type workloads such as Microsoft Office or general knowledge workers applications may require 1GB of memory per user session, topping your concurrent sessions at 14 users per HAS.
You should also consider whether or not you want to buffer in case individual user session go over their average predicted requirements.
If you need a tool to help assess your user session deployment, you can sign up for 30 days free trial of VMware's assessment service at http://assessment.vmware.com
We hope this information helps you get started with Hosted Applications and let us know if you have any more questions.
The Horizon Air Team