καὶ εἰ θέλετε δέξασθαι, αὐτός ἐστιν Ἠλίας ὁ μέλλων ἔρχεσθαι.

1. καὶ
   and
2. εἰ
   if
3. θέλετε
   do you want
   you want
4. δέξασθαι
   to receive
5.  
   ,
    
6. αὐτός
   himself
   he
7. ἐστιν
   is
8. Ἠλίας
   Elijah
9. ὁ
   the
10. μέλλων
    intending
    being about, being about to
11. ἔρχεσθαι
    to come
12.  
    .
     

and if you want to receive it, he is Elijah who is about to come.