Can "Confirm Email" be below "Enter Email" instead of side by side?

By default they appear side by side. There isn't a built in option to make them appear stacked. However, anything can be done using some custom CSS.

If you want to tell those fields not to float you'd have to override the default Gravity Forms styles that are being applied by adding custom CSS to your themes stylesheet.

Add this to the very end of your themes stylesheet:

.gform_widget #gform_wrapper_1 #input_1_1_1_container {float: none!important; width: 90%}
.gform_widget #gform_wrapper_1 #input_1_1_2_container {float: none!important; width: 90%}

That code targets those specific inputs on that specific form in a widget and disables the float being applied to those spans and then redefines the width so it fills the additional space.