OFDM symbol synchronization
CP based Symbol Boundary detection algorithm which is fundamentally based on correlation will still work. You just need to do a timing recovery before FFT operation. 

A small offset in sampling times will cause a small phase rotation in pilots and these small rotations are used to compute the timing offset. 

Once you have a good timing offset estimate, you do timing recovery on the received samples of OFDM symbol. Timing recovery is nothing but doing some low cost polynomial interpolation to get the actual values of the samples at correct sampling times. 

Or in OFDM once you have these timing offsets as phase rotation, derotate rest of the data symbols after FFT before slicing to get the complex QAM symbols.