No, there is no direct train from Guangzhou to Fuzhou. If you would like to take a train, you have to get to Xiamen(https://www.travelchinaguide.com/cityguides/fujian/xiamen/) from Guangzhou firstly. Everyday, there are two trains departing to Xiamen from Guangzhou East Railway Station, taking about 14 hours and 320RMB/sofe-sleeper. After arrive at Xiamen, You could transfer to a CRH D-train to Fuzhou in 1.5 hours.

The Guangzhou Train Tickets(https://www.travelchinaguide.com/china-trains/guangzhou-schedule.htm) could be purchase at the ticket halls of any railway stations. If you are not in China, it is suggested that you ask some agents for help in case of the tickets are needed urgently. You could purchase the Xiamen Train Tickets(https://www.travelchinaguide.com/china-trains/xiamen-schedule.htm) on the spot at the railway station or by the help of an agent, too. Hope this helps!