。
She is everything to him.
Literal
She [topic-は] him [for-contrast-にとっては] everything is.
The は after にとって ('にとっては') makes the perspective topic-contrastive — 'as for him specifically (vs. others).' Without は, plain にとって just states the perspective; with は, it implies a contrast with other people's views. 全て ('everything, all') is the noun for totality. The whole sentence is a strong romantic declaration — 'she is his everything.'