Traditionally, there are three ways to attain moksha: Jnana, Bhakti, and Karma.
Is it true that it will take more time for a person to attain moksha in Jnana marga?
Karma (i.e. doing actions following Dharma), Bhakti will gradually lead to Jnana and Jnana liberates.
O King of mountains! Meditation with Karma and Jñâna with Bhakti will lead one to Me. Only the work alone will fail to get one to Me. O Himavan! From Dharma arises Bhakti and from Bhakti arises the Highest Jñâna. What are said in the S'ruti and Smriti S'astras the Maharsis take that as the Dharma; and what are written in other S'astras,
So, naturally (and usually) the Jnana stage takes most time and effort to reach.