Is it possible to estimate the restore progress in SQL Server 2014 from pages read/written?
Look at percent_complete and estimated_completion_time in sys.dm_exec_requests. If it is in fact populated for restoring logs (I have only tested full database restores), it is going to be based on the same math you want to try and calculate manually.

SELECT percent_complete, estimated_completion_time
  FROM sys.dm_exec_requests
  WHERE session_id = &lt;SPID running the backup&gt;;


Obviously neither approach can predict pending concurrency / I/O interruptions, so it is nowhere near any sort of guarantee - just a ballpark guess. It also won't be possible to predict how much I/O will be required for any undo/redo operations, since these are not directly related to the size of the log.