Unless you're tracking roles on the starting form with some custom lookup you wouldn't really have a way to "skip" step B through a gateway since role evaluation is really just for task assignment.

However, what you could do is set the Start Event option for "automatically load the next task when the same person is assigned to it" so it is more seamless.

Then in the task use a dynamic filter on the team that checks if the user has the role, if yes, assign it to them and it should load just after they submit, if not, assign it to the team members in that role.

var submitter = team.findTaskLastSubmitters(1);
var usersInRole = team.findMembersByRole('Test');
var user = $util.intersection(submitter, usersInRole);

$result = user.length > 0 ? user : usersInRole;

This filter gets the submitter for the Step 1 (the start should be 1, but double check the step id in the top right of the details pane when you click on the start event).

Next, it retrieves all the users with the desired role from the team and checks for an intersection between the two results (i.e., if the submitter is also in that role).

Lastly, it checks to see if there was an intersection result. If so, it assigns the task directly to that user. If not, it assigns it to the users who are in the role using the full list it retrieved.

You can also evaluate variables in the filter if you need your role value to be dynamic.