Yeap, My honest opinion..
You should not go for the interview. I don't think you are ready. However, you might be lucky and person asking questions might just ask same questions or they might not know what to ask you..
ETL is a broad term. Do you know what software - SSIS or any other ETL ?..
A friend of mine was asked to create a SSIS package during the interview. These days most hiring mangers are aware of this fake resume.
Recently a guy at my work was terminated on 1st day. When I asked the PM, he told me that its not the same guy they interview on the phone. Basically they asked him same question and he couldn't answer...
Now back to your question (since I assume it is SSIS etl) , I have only used some other ETL to some extend so I cannot comment on them
E - Extract (all diff sources)
T - Transform ( data manipulation )
L - Load ( all diff destinations)
This is the basic of ETL. I don't know what you have in your resume so I cannot give any scenerio examples ...
But Go over basic stuff for SSIS. Find some of the major used Task in SSIS and read when they are used. GO read DataFLow task, FInd what are diff sources and destinations...find what are major data manupulations tasks used for data flow
SSIS configuration and dynamic and variables are major in SSIS, read them ...
Google some of the challenging stuff ppl have faced in SSIS (one of them is adding Header and Trailer records which deisn't match output layout)
One drawback no secure FTP only FTP in SSIS (not sure if they have in 2014)
Read lookup Task and diff settings on it..
How to call this SSIS in job and diff settings of SSIS when it comes to security
How they are stored - 3 types
Deployment method

Hope this helps