Hi, if I arrive in Guilin in the afternoon can I still take a river cruise to Yangshuo?

You can not take the cruise ship in the afternoon. It usually departs in the morning, around 09:00. You can take the bamboo raft at that time, but it is not so safe, and you may be cheated to pay a high cost. I do not advise you to take it. If you really want to experience the bamboo rafe, you can try to bargain down the price and be careful.