How can I find out what stats objects were used during a SQL Server 2014 query?
Yes, it’s flag 2363! Flag 3604 is just for redirecting the debugging output to the Messages window, so that stays the same in 2014.

SQL Server 2012

SELECT * FROM Test
WHERE Pred1 = 1 AND Pred2 = 2
OPTION
(
QUERYTRACEON 3604,
QUERYTRACEON 9292,
QUERYTRACEON 9204
)


SQL Server 2014

SELECT * FROM Test
WHERE Pred1 = 1 AND Pred2 = 2
OPTION
(
QUERYTRACEON 3604,
QUERYTRACEON 2363
)


Source: the SQL Server 2014 Selectivity Trace Flags section on this link.