Hello,
currently svn can be accessed via ldap credentials,
I would like to protect the service some sort of mfa.
Is there any possibility to do that with privacyidea?
My users are either using command line or tortoise svn clients (not web based systems).
As with all applications you have to look into what protol it supports or how the authentication stack looks like.
Some applications allow for adding your own modules into the authentication stack.
I do not know about svn. It was claimed to be this mordern thingy when everybody was fed up with cvs, righ? I have not used it for decades and did not look into it.
Maybe it uses PAM? This would be an angle to look at. Then you could simply use pam_radius.
If supports LDAP, you could use the privacyIDEA ldap proxy, but I would never ever recommend this, because the ldap proxy is so complicated (since authentication with ldap is not well defined and thus can be complicated) that you would never stop asking questions 
If PAM, go for PAM.