Exegesis:

ho Iēsous ethaumasen auton ‘Jesus marvelled at him,’ rather than ‘admired him.’

strapheis tō akolouthounti autō ochlō ‘turning to the crowd that he followed him.’ autō is dependent upon akolouthounti.

strapheis (7.9, 44; 9.55; 10.23; 14.25; 22.61; 23.28) aorist participle of strephomai ‘to turn,’ in Luke always in this form and always referring to Jesus, used to denote that Jesus turns his attention to others, or to some people specifically.

legō humin ‘I say to you,’ cf. on 3.8.

oude en tō Israēl tosautēn pistin heuron ‘not even in Israel have I found faith so great.’ Israēl refers to the Jewish nation as a geographical and religious entity. tosautēn lit. ‘so great,’ is best understood in a qualitative sense, cf. Revised Standard Version. For pistis cf. on 5.20. heuron, aorist, expresses that the action is completed and now regarded as a whole in contrast with what Jesus found at that very moment.

Translation:

Marvelled at, see on “wondered at” in 1.21.

Turned and said to the multitude, or, ‘turned (around) towards the multitude, saying/and said.’ To turn (or, ‘to turn the face,’ ‘to look back’), i.e. in order to address, hence in some cases, ‘to address.’

Followed, or, ‘went along with him,’ ‘was/walked behind (him),’ referring to accompaniment, not to discipleship.

Not even in Israel have I found such faith, or, ‘even in (the people) Israel I have not found a man who believed so strongly (in me),’ or, ‘this man believes very firmly (in me); even amongst Israelites I have not met/come-across the like of him.’ — Even is often expressed by an intensive particle indicating what might not be expected, and/or by giving emphatic position to the word(s) it qualifies. — In Balinese such faith is idiomatically rendered as, ‘faith that is so dense.’

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.