1. Update rsyslog(syslog) configuration

vi /etc/rsyslog.conf

#sftp logging
local5.*                                -/var/log/sftpd.log

service rsyslog restart

2. SSHD Configuration file

vi /etc/ssh/sshd_config 

Subsystem sftp /usr/lib/ssh/sftp-server -f LOCAL5 -l INFO

service sshd restart