You can hide this page using following code

<xpath expr="//page[@string='Invoice Lines']" position="attributes">                   

     <attribute name="attrs">{'invisible': [('state','!=','draft')]}</attribute>               

</xpath>

try with domain filter,

<field name="domain">[('state', '!=', 'draft')]</field>

<field name="arch" type="xml">

    <xpath expr="//page[@string='Invoice Lines']" position="replace">

        <!-- nothing here-->

    </xpath>

    <!-- OR -->

    <xpath expr="//page[@string='Invoice Lines']" position="attributes">

        <attribute name="invisible">True</attribute>

    </xpath>

</field>