Nope, the GW cannot send the log data to any other server in syslog format, and as you are on a multidomain you cannot install a local log server either, as that is not supported until R81.
We have a similar issue where we run a R77.30 MDS with customers that use local per domain log servers, in their private area so they have the log locally and I do not want those servers in the global domain, as that is the only way to add a log server now.
The log server in the DMZ of the customers FW is recewiving the data local to their network and forwarding it from their with cplog exporter to Qradar.
Regards, Maarten