Marvell's poem persuades by means of ethos, logos, and pathos, and uses luxuriously sensual language to suggest by parallelism that a similar sensuality would be part of a physical as well as the verbal encounter.
The basic logic of the poem is syllogistic. It suggests that were humans immortal, she could delay consummation of their relationship with his enthusiastic collaboration, but humans are not immortal, and thus they should not delay.
He projects an appealing ethos as a lover in the long description of how he would, were they immortal, devote extended attention to each part of her body, suggesting that he is a skilled and attentive lover.
He manages pathetic appeal by using beautiful descriptive language to evoke an image of sensual pleasure that will appeal to her own physical desires.