Both teams are demonstrating an inconsistent defensive performance, which is confirmed by the statistics: Tottenham have conceded regularly in recent matches (two goals each against Manchester United and Burnley), while Newcastle have conceded 10 goals in their last five games. However, both teams are capable of scoring in attack – Spurs have found the net in each of their last matches, while the Magpies have found the net in three of their last five.
Their head-to-head record also points to a high probability of a mutually beneficial outcome. In the last five games between these teams, goals have been exchanged in all matches, with both sides scoring in four of those. They have already drawn 2-2 in the Premier League this season, confirming their tendency to play openly with plenty of opportunities.
Given the current form, motivation of the teams battling for the top half of the table, and their penchant for attacking football, it's logical to expect both teams to score.