You need as many moles of Ti4+ as the number of moles of methylamine added, as they bind to each other in a 1:1 fashion. This complex then in turn adds to the ketone forming a so-called (methylamino)carbinolatotitanium(IV) complex as an intermediate which is reduced either directly or via transient iminium species.
See the following articles for details:
Reductive Alkylations of Dimethylamine Using Titanium(IV)Isopropoxide and Sodium Borohydride:
An Efficient, Safe, and Convenient Method for the Synthesis of N,N-Dimethylated Tertiary Amines
Sukanta Bhattacharyya
J. Org. Chem. 60, 4928-4929 (1995) (https://www.thevespiary.org/rhodium/Rhodium/pdf/redamin.nabh4-ti4-me2nh.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/redamin.nabh4-ti4-me2nh.pdf)
A New Method for the Synthesis of alpha-Substituted Phenethylamines via Titanium Amide Complexes
Synthesis 238-240 (1988) (https://www.thevespiary.org/rhodium/Rhodium/pdf/titanium.amide.amphetamines.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/titanium.amide.amphetamines.pdf)