The referenced article suggests that while Cloud has romantic tension with Aerith, his feelings appear stronger for Tifa.
The article directly states that separate dates with Aerith and Tifa "make it clear who Cloud really likes." This implies a difference in the intensity of his feelings. While the date with Aerith has romantic tension and hand-holding, the connection with Tifa seems more profound. The reference doesn't go into specific details on why Cloud liked one more than the other, but it is explicit in that the date dynamics displayed who Cloud had a higher preference toward.
