Can I give Zakat to a revert who has money to survive but isn’t steadfast upon din?

In the Name of Allah, the Most Gracious, the Most Merciful.  

As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.  

In principle, it is only permissible for one to dispense Zakah to the valid recipients of Zakat. A valid recipient of Zakah is regarded as a person who is a muslim and does not possess the nisab of Zakat or its equivalent value.  

Any individual who possesses  

1. less than his basic necessities, or 
2. less than two hundred dirhams (612.36 grams of silver) or twenty dinars (87.47 grams of gold), or its equivalent, over and beyond his basic necessitates will be regarded as a valid recipient of Zakah. 

Accordingly, if he does not possess the Nisab amount he may be given Zakah. Alternatively, you may give him Sadaqah or grant him gifts to aid him through these difficult times