Sources have told ESPN's James Olley that there is an option to make the deal permanent for around £36 million.
Spurs head coach Jose Mourinho has been desperate to bolster his attacking options and provide cover for Harry Kane, the club's only out-and-out striker in the first-team squad.
The 25-year-old, who has never been capped at senior international level for Brazil, joined Benfica from Napoli last summer and scored 24 goals in the 2019-20 campaign.
Mourinho underlined his concern at the lack of cover for Kane prior to Tuesday's Carabao Cup penalty shootout win over Chelsea, claiming that with Kane left on the bench for a breather, he "had nobody" to play as a conventional striker.
He has, however, been confident throughout the last few weeks that Spurs would eventually sign another striker and that faith has now been vindicated with Vinicius finalising a move to north London.