If you are using a relayed session with Android SDK, the maximum number of participants is 2 (1:1).
For routed sessions OpenTok Android SDK can support more than one published/subscribed audio-video stream. However, please note that network connectivity and device specs can greatly affect and limit the quality of the streams. In our experience, creating more than three published/subscribed audio-video streams can result in poor stream quality due to CPU limitations. On some devices you might be able to do more by optimizing the following settings: lowering the resolution, the frame rate, or switching to audio-only.