Hugh Ross has claimed that numerous church fathers held old-earth viewpoints, but listen to what a couple of old-earth Christians themselves admit:
“In his book Creation and Time (Colorado Springs: Navpress, 1994), astrophysicist and Christian apologist Hugh Ross conveyed the impression that there was a wide range of opinions about the nature of the creation days in the early church. He maintained that “writing later in the third century, Lactantius (c. AD 250-325), Victorinus of Pettau and Methodius of Olympus, all concurred with Justin Martyr’s and Irenaeus’s view of the creation days as thousand-year epochs” (p. 19). He also wrote that “throughout the Dark and Middle Ages, church scholars maintained the tolerant attitude of their forefathers toward differing views and interpretations of the creation time scale” (p. 25)
“We are unable to agree with Ross’s assessment of the views of the early church. The first quotation is incorrect because the church fathers did not believe that the days of creation were 1,000 years long, but they did believe that 1,000 years of human history corresponded to each literal day of creation [i.e. there would be only 6,000 years of human history after the creation]. The second quotation is somewhat misleading because it conveys the impression that the church fathers might have differed about the time of creation, but we have no evidence that anyone other than Origen [of Alexandria] thought the world might be older than 5,500 years [using the Septuagint].”
From The Bible, Rocks and Time by Davis A. Young & Ralph F. Stearley, 2008, Intervarsity Press, p. 34.