Question: is the tense of a verb an infinitive

Answer: No, Being a verb, an infinitive may take objects and other complements and modifiers to form a verb phrase (called an infinitive phrase). Like other non-finite verb forms (like participles, converbs, gerunds and gerundives), infinitives do not generally have an expressed subject; thus an infinitive verb phrase also constitutes a complete non-finite clause, called an infinitive (infinitival) clause. Such phrases or clauses may play a variety of roles within sentences, often being nouns (for example being the subject of a sentence or being a complement of another verb), and sometimes being adverbs or other types of modifier. Many verb forms known as infinitives differ from gerunds (verbal nouns) in that they do not inflect for case or occur in adpositional phrases. Instead, infinitives often originate in earlier inflectional forms of verbal nouns. Unlike finite verbs, infinitives are not usually inflected for tense, person, etc. either, although some degree of inflection sometimes occurs; for example Latin has distinct active and passive infinitives.