'On what wings dare he aspire?' why does the poet pose this question?

The poem is is actually a long list of questions, each stanza refines the stanza that comes before. In this specific line, the poet is questioning his initial observation.... the creation of the tyger, the type of creator who could fashion such a fearsome beast. The "wings" in the line you've provided symbolize the "power" of the creator...... the essence that provides inspiration and provides for the creation itself.