1. An image processing system comprising: a server apparatus connected to a first network; an image processing apparatus connected to a second network; and a gateway apparatus configured to connect the second network to the first network, perform mutual conversion between a first communication protocol being used in the first network and a second communication protocol being used in the second network, and relay communication between the server apparatus and the image processing apparatus, wherein the server apparatus includes a first hardware processor configured to: transmit job data of a job by the first communication protocol, the image processing apparatus being made to execute the job; and add content information to the job data, the content information indicating contents of the job, and the gateway apparatus includes a second hardware processor configured to: analyze the job data and acquire the content information; determine whether the image processing apparatus is capable of executing the job based on the content information; and execute an operation related to the job based on a result of the determination performed by the hardware processor, the image processing system further comprising: a log server connected to one of the first network and the second network, wherein the job includes a transfer job to transfer information about an image to the log server, the image being an image to be formed by the image processing apparatus, and, when the image processing apparatus is not capable of executing the transfer job, the second hardware processor of the gateway apparatus acquires print data from the job data, transmits the acquired print data to the image processing apparatus, and transmits the print data or data corresponding to the print data to the log server.