You should use a user task to model the approval request, and use a result mapping to map the answer to a process variable. You can then use this variable in for example an exclusive gateway to make a decision based on the response of the user.
There is an example in the jbpm-examples module that does something similar: use a human task to ask for approval: https://github.com/droolsjbpm/jbpm/blob/master/jbpm-examples/src/main/resources/humantask/HumanTask.bpmn
Kris